Post by anansi on Aug 11, 2024 12:26:02 GMT -5
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A General History of Iron Technology in Africa ca. 2000BC-1900AD.
The smelting and working of iron is arguably the best known among the pre-colonial technologies of Africa, and the continent is home to some of the world's oldest sites of ironworking.
Iron metallurgy was an integral component of socioeconomic life across the continent, and has played a significant role in the sociocultural, economic, and environmental spheres of many African societies, past and present, not only for utilitarian items, but also in the creation of symbolic, artistic, and ornamental objects.
The production, control, and distribution of Iron was pivotal in the rise and fall of African kingdoms and empires, the expansion of trade and cultural exchange, and the growth of military systems which ensured Africa’s autonomy until the close of the 19th century.
This article outlines the General History of Iron technologies in Africa, from the construction of the continent's oldest furnaces in antiquity to the 19th century, exploring the role of Iron in African trade, agriculture, warfare, politics, and Art traditions.
On the invention of Iron technology in Africa.
Most studies of the history of Ironworking begin with the evolution of metallurgy in the Near Eastern societies and the transition from copper, to bronze and finally to iron. The use and spread of these metals across the eastern Mediterranean was a complex and protracted process, that was politically and culturally mediated rather than being solely determined by the physical properties of the metals.1
Since the transition from copper to iron across most of the societies in the Near East was broadly similar, and the region was initially thought to be home to the oldest known iron-working sites, researchers surmised that iron technology had a single origin from which it subsequently spread across the old world from Asia to Europe, to Africa.
In North Africa, ironworking was only known from historical documents, it was only recently that archeological investigations have provided firmer evidence for early iron smelting in the region. This includes sites such as Bir Massouda at Carthage in Tunisia between 760-480 BCE2, at Naucratis and Hamama in Egypt between 580-30BCE3, at Meroe and Hamadab in Sudan around 514 BCE4 and in the Fezzan region of Libya around 500BCE5.
Large iron slag mound at Meroe, Sudan. photo by Jane Humpris.
However, as it will become evident in the following paragraphs, the development of iron technology in the rest of Africa was independent of North African ironworking and is likely to have been a much older phenomenon. In contrast to the Maghreb, metallurgy in the rest of Africa kick-started with the simultaneous working of iron and copper between the late 3rd to early 2nd millennium BC, to be later followed by bronze, gold and other metals.
A number of radiocarbon dates within the range of 2200 to 800 BCE have since been accumulated across multiple sites. This includes sites such as Oboui and Gbatoro in Cameroon and Central Africa, where iron furnaces, bloom fragments, slag pieces, and at least 174 iron tools were found dated to c. 2200–1965 BCE, at Ngayene in the Senegambian megaliths, where iron tools were found dated to 1362–1195 BCE, and at Gbabiri (north of Oboui) where similar iron objects and forges were found dated to 900–750 BCE.6
More extensive evidence for iron working in West Africa is dated to the period between 800-400 BCE, where the combined evidence for iron tools, furnaces, slag, and tuyeres was found at various places. These include the sites of Taruga and Baidesuru in the Nok culture of central Nigeria, In the northern Mandara region of Cameroon, at Dhar Nema in the Tichitt Neolithic culture of southern Mauritania, at Dia In the Inland Niger delta of Mali7, at Walalde in Senegal8, at Dekpassanware, in Togo9 at the Nsukka sites of Nigeria,10 and at Tora Sira Tomo in Burkina Faso11, among other sites.
Slag blocks at Otobo-Dunuoka village square, Lejja, Nsukka area, Nigeria.
The subsequent spread of ironworking technology to central, East and South Africa was linked to the expansion of Bantu-speaking groups, a few centuries after they had settled in the region.12 For the period between 800-400BC Iron working sites, are found at Otoumbi and Moanda in Gabon, at the Urewe sites of; Mutwarubona in Rwanda, Mirama III in Burundi, at Katuruka in Tanzania.13
By the turn of the common era, Ironworking had spread to the southeastern tip of the continent, with sites such as Matola in Mozambique and ‘Silver Leaves’ in South Africa being dated to between the 1st-2nd century CE.14 While few studies have been conducted in the northern Horn of Africa, there’s evidence for extensive use of iron tools at Beta Giogyis and Aksum in Ethiopia, between the late 1st millennium BC and the early centuries of the common era. 15
While proponents of an independent origin of iron technology in Africa rely on archeological evidence, the diffusionist camp is driven by the hypothesis that ironworking required pre-existing knowledge of copper smelting, they therefore surmise that it originated from Carthage or Meroe. However, there's still no material evidence for any transmission of ironworking technology based on the furnace types from either region16, and the recently confirmed dates from Cameroon, Central Africa, and Senegal significantly predate those from Meroe, the Fezzan, and Carthage.17
Furthermore, there was no contact between the earliest West African Iron Age sites of the Nok Culture with North Africa; nor was there contact between Nok and its northern neighbor; the Gagijana culture of Lake Chad (1800-400BCE) which had no iron at its main proto-urban capital of Zilum;18 nor were there links between Carthage and Zilum during this period. Even links between more proximate regions like the Fezzan in Libya (which had Iron by 500 BCE) and the Lake Chad basin before the common era remain unproven.19
The site of Oboui in the Central African republic has been the subject of intense interest by archeometallurgists since it provides the earliest known iron-working facility anywhere in the world.
So while it may "never be possible to write a history of African metallurgy that truly satisfies the historian's inordinate greed for both generalization and specificity," the most recent research weighs heavily in favor of an independent origin of Ironworking in Africa.
1st millennium BC Nok furnace site at Janjala, Nigeria.
The process of Smelting and Smithing Iron in African furnaces.
The process of ironworking starts with the search and acquisition of iron ores through mining and collecting, followed by the preparation of raw materials including charcoal, followed by the building of the smelting installations, furnaces, tuyeres and crucibles, followed by the smelting itself which reduces the ores to metal, followed by bloom cleaning, smithing, and the forging of the finished product20. This was extremely labour-intensive and time-consuming, especially collecting the ore and fuel, which could at times last several weeks or months.21
In nature, iron may be found in five different compounds: oxide, hydroxide, carbide, sulfide, and silicate, of which there are many different types of iron ores in Africa (lateritic, oolitic, magnetite-ilmenite, etc) which invariably influenced the smelting technology used. Ancient African bloomery furnaces exhibit remarkable diversity, suggesting constant improvisation and innovations. As one metallurgist observed, "every conceivable method of iron production seems to have been employed in Africa, some of it quite unbelievable." African ironworkers adapted bloomery furnaces to an extraordinary range of iron ores, some of which cannot be used by modern blast furnaces and weren’t found anywhere else in the Old World.22
African iron-smelting processes are all variants of the bloomery process, in which the air blast must be stopped periodically to remove the masses of metal (blooms), while the waste product (slag) may be tapped from the furnaces as a liquid, or may solidify within it. Most of the oldest African furnaces were shaft furnaces that ranged from small pit furnaces to massive Natural-draft smelting furnaces with tall shafts upto 7 meters high.23
Natural draft furnaces in the Seno plain below Segue, Burkina Faso, 1957, Quai Branly. Earthen smelting furnaces in Ouahigouya, near the capital of Yatenga kingdom, Burkina Faso, 1911, Quai Branly.
Examples of African bloomery furnace types (by F. Bandama), Approximate distribution of bowl, shaft, and natural draught furnace types in Africa. (by S. Chirikure).
Bloomery smelting operates around 1200°C; ie at a temperature below the melting point of iron (1540°C), which is high enough only to melt the gangue minerals in the ore and separate them from the unmolten iron oxides. Air is introduced to the furnace either through forced draft using bellows and tuyères (ceramic pipes), or by natural draft taking advantage of prevailing winds or utilizing the chimney effect. This enables the fuel (usually charcoal) to burn, producing carbon monoxide, which reacts with the iron oxide, ultimately reducing it to form metallic iron.24
These furnaces could produce cast iron and wrought iron, as well as steel, the latter of which there is sufficient evidence in several societies, most notably in the 18th-century kingdom of Yatenga between Mali and Burkina Faso, where blacksmiths built massive furnaces upto 8m high to produce steel bars and composite tools with steel-cutting edges25. Steel is iron alloyed with between 0.2% and 2% carbon, and it has been found in archaeometallurgical studies of furnaces and slag from Buhaya in northern Tanzania,26 and in northern Mandara region of Cameroon among other sites.27 Most high-carbon steel could be produced directly in the bloomery furnace by increasing the carbon content of the bloom, rather than by subsequent smithing as in most parts of the Old World.28
Iron smelting at Oumalokho near the border of Mali & Cote d’ivoire, illustration by Louis Binger, ca. 1892
steel sword with gold hilt, blade decorated with incised geometric and floral decoration, ca. 1900, Asante, Ghana, V&A museum
Once smelting was complete, the bloom settled to the bottom of the furnace and was removed for further refinement through repeated heating and hammering into bars using large hammerstones. After which, the iron bars produced from this process were forged at high temperatures, and the blacksmith will use various hammers, tongs, quenching bowls, and anvils to work the iron into a desired shape. In a few cases, methods like lost wax casting and the use of molds which were common in the working of gold and copper alloys were also used for iron to produce different objects, ornaments, and ingots.29
Like all forms of technology, the working of Iron in Africa was socially mediated. The role of blacksmiths was considered important but their social position was rather ambiguous and varied. Depending on the society and era, they were both respected or feared, powerful or marginalized, because they wielded social power derived from access to knowledge of metallurgy, divination, peacemaking, and other salient social practices30.
The smith’s craft extended from the production of the most basic of domestic tools to the creation of a corpus of inventive, diverse, and technically sophisticated vehicles of social and spiritual power The various taboos and rituals associated with the craft were a technology of practice that enabled smelters to take control of the process through learned behavior.31
One key feature of African metallurgy is that it resists homogenization, yet anthropologists who study the subject are more inclined to homogenize than to seek variations. In contrast to the making of pottery and sculptures, the apprenticeship of iron smelting has not been the focus of ethnological studies. While such studies can only provide us with information from the 20th century, the persistence of pre-industrial methods of iron production in some parts of the continent suggests that some of this information can be extrapolated back to earlier periods.
A number of researchers have left ethnographic descriptions of smelting sessions that they attended, observing that there is a head smelter or an elder’s council, as well as young people or apprentices. Under the leadership of a master, the metallurgists seem to take part collectively in the smelting, and the associated rituals involved in the process. Each member of a smelting session detects the physical and chemical changes of the material being processed inside the furnace.32
Ethnographic descriptions show the major importance of smith castes and ritual practice, as well as political control over resources like iron ore, wood, land, and labour.33 In many parts of the continent, there's extensive evidence that iron smelting was considered ritually akin to the act of procreation and therefore was carried out away from or in seclusion from women and domestic contexts34. Yet there were numerous exceptions in southern and East Africa where women were allowed in the smelting area, procuring iron ores, and constructing furnaces.35
Evidently, all available labour was utilized for iron working when necessary, depending on the cultural practices of a given society.
The role of Iron in early African Agriculture and Trade.
Ironworking played a pivotal role in the advent and evolution of agriculture and long-distance trade across the African continent, as the widespread use of iron tools helped to increase food production and the exchanges of surpluses between different groups. In many societies, the various types of iron tools (such as plows and hoes) the design of furnaces, and the organization of labor, influenced and were influenced by developments in agriculture, trade, and cultural exchanges.36
For example, the use of natural draught furnaces and the creation of a caste of blacksmiths frees up labour for working the raw iron to make iron objects and develop long-distance trade and exchange. Such furnaces high fuel-low labour furnaces were particularly common in the West African Sudanic woodland zone from Senegal to Nigeria and in the miombo woodlands of Tanzania, Zambia, Malawi and Mozambique, where labour requirements for swidden agriculture may have reduced available labour for smithing.
Natural draft furnaces; Yeke, D.R.Congo, early 20th century, Royal Museum for Central Africa. Aushi, Zambia, early 20th century, British Museum. ‘A Bafipa natural draft furnace in Tanzania’, photo by S.T.Childs.
In other regions, the demand for Iron objects beyond the immediate society in which specialist smiths lived facilitated the production of large quantities of Iron for export. For example, at least 15 sites used by Dogon smiths in south-central Mali produced a about 400,000 tonnes of slag – or 40,000 tonnes of iron objects over a period of 1,400 years, about 26 tones of iron objects per year while the site of Korsimoro (Burkina Faso) yielded 200,000 tonnes of slag - or 20,000 tonnes of iron objects between 1000-1500 CE, about 32 tonnes of iron per year.38
This scale of production doubtlessly suggests that the iron was intended for export to neighboring societies, albeit not at a scale associated with large states. For example, the dramatic rise in iron production from a small site of Bandjeli in Togo, from less than a tonne in the 18th century to over 14 tones per year by 1900 may have been associated with demand from sections of the kingdoms of Dagomba, Gonja, Mamprusi, although it was far from the only site39. It therefore appears that in most parts of Africa, specialization was based on pooling together surplus from various relatively small-scale industries which cumulatively produced bigger output, and may not have been concentrated even in the case of large states.40
Several types of iron objects served as convenient stores of value and were at times used as secondary currencies in some contexts, primarily because of the ever-present demand for domestic and agricultural iron implements like hoes, knives, machetes, harpoons, as well as the general use of metals for tribute, social ceremonies, and trade.41
In West Africa, iron blooms were traded and kept as heirlooms, while knives and iron hoes were both a trade item and a medium of exchange in parts of Southern Africa and west-central Africa42. In East Africa, where long-distance traders like the 19th century Swahili traveler Mwenyi Chande were required by local rulers to give iron hoes as a form of tax on their return journeys from the interior as a substitute for cowries and cloth. Similary In Ethiopia, iron plowshares were valued items of trade.
Illustration depicting an ‘Abyssinian Plough’. ca. 1868, Library of Congress.
Iron in the History of Warfare and Politics in Pre-colonial Africa.
Given its centrality in agriculture and trade, the spread of iron working in Africa was closely associated with the emergence and growth of complex societies across the continent.
The rise of African states resulted in an increased demand for symbols of prestige and power, among which iron, copper, and gold were prominent. Increase in metal production and changes in furnace construction in the Great Lakes region for example, were associated with the emergence of the kingdoms of Bunyoro, Buganda, and Nyiginya (Rwanda),44 and similar developments in southern Africa and the East African coast were associated with the rise of the kingdoms at Great Zimbabwe and Kilwa.45
A significant number of iron tools found at the oldest sites of ironworking across the continent included knives and arrowheads. Additionally, a number of historical traditions of societies in central Africa like the kingdom of Ndongo and Luba, either attribute or closely associate the founding of kingdoms to iron-wielding warrior-kings and blacksmiths46. Iron was often conceptually integrated within the organizing structures of these states, with iron symbolism frequently incorporated within iconography, mythology, and systems of tribute payment, all of which underscores the importance of iron weapons to the emergence and expansion of African kingdoms and empires, especially in warfare.
Sword made by a Ngala smith from Congo, Copper alloy handle with iron struts attached to iron blade, Late 19th century, Saint Louis art museum
Iron Sword, 19th century, Asante Kingdom, Ghana, British Museum
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A General History of Iron Technology in Africa ca. 2000BC-1900AD.
The smelting and working of iron is arguably the best known among the pre-colonial technologies of Africa, and the continent is home to some of the world's oldest sites of ironworking.
Iron metallurgy was an integral component of socioeconomic life across the continent, and has played a significant role in the sociocultural, economic, and environmental spheres of many African societies, past and present, not only for utilitarian items, but also in the creation of symbolic, artistic, and ornamental objects.
The production, control, and distribution of Iron was pivotal in the rise and fall of African kingdoms and empires, the expansion of trade and cultural exchange, and the growth of military systems which ensured Africa’s autonomy until the close of the 19th century.
This article outlines the General History of Iron technologies in Africa, from the construction of the continent's oldest furnaces in antiquity to the 19th century, exploring the role of Iron in African trade, agriculture, warfare, politics, and Art traditions.
On the invention of Iron technology in Africa.
Most studies of the history of Ironworking begin with the evolution of metallurgy in the Near Eastern societies and the transition from copper, to bronze and finally to iron. The use and spread of these metals across the eastern Mediterranean was a complex and protracted process, that was politically and culturally mediated rather than being solely determined by the physical properties of the metals.1
Since the transition from copper to iron across most of the societies in the Near East was broadly similar, and the region was initially thought to be home to the oldest known iron-working sites, researchers surmised that iron technology had a single origin from which it subsequently spread across the old world from Asia to Europe, to Africa.
In North Africa, ironworking was only known from historical documents, it was only recently that archeological investigations have provided firmer evidence for early iron smelting in the region. This includes sites such as Bir Massouda at Carthage in Tunisia between 760-480 BCE2, at Naucratis and Hamama in Egypt between 580-30BCE3, at Meroe and Hamadab in Sudan around 514 BCE4 and in the Fezzan region of Libya around 500BCE5.
Large iron slag mound at Meroe, Sudan. photo by Jane Humpris.
However, as it will become evident in the following paragraphs, the development of iron technology in the rest of Africa was independent of North African ironworking and is likely to have been a much older phenomenon. In contrast to the Maghreb, metallurgy in the rest of Africa kick-started with the simultaneous working of iron and copper between the late 3rd to early 2nd millennium BC, to be later followed by bronze, gold and other metals.
A number of radiocarbon dates within the range of 2200 to 800 BCE have since been accumulated across multiple sites. This includes sites such as Oboui and Gbatoro in Cameroon and Central Africa, where iron furnaces, bloom fragments, slag pieces, and at least 174 iron tools were found dated to c. 2200–1965 BCE, at Ngayene in the Senegambian megaliths, where iron tools were found dated to 1362–1195 BCE, and at Gbabiri (north of Oboui) where similar iron objects and forges were found dated to 900–750 BCE.6
More extensive evidence for iron working in West Africa is dated to the period between 800-400 BCE, where the combined evidence for iron tools, furnaces, slag, and tuyeres was found at various places. These include the sites of Taruga and Baidesuru in the Nok culture of central Nigeria, In the northern Mandara region of Cameroon, at Dhar Nema in the Tichitt Neolithic culture of southern Mauritania, at Dia In the Inland Niger delta of Mali7, at Walalde in Senegal8, at Dekpassanware, in Togo9 at the Nsukka sites of Nigeria,10 and at Tora Sira Tomo in Burkina Faso11, among other sites.
Slag blocks at Otobo-Dunuoka village square, Lejja, Nsukka area, Nigeria.
The subsequent spread of ironworking technology to central, East and South Africa was linked to the expansion of Bantu-speaking groups, a few centuries after they had settled in the region.12 For the period between 800-400BC Iron working sites, are found at Otoumbi and Moanda in Gabon, at the Urewe sites of; Mutwarubona in Rwanda, Mirama III in Burundi, at Katuruka in Tanzania.13
By the turn of the common era, Ironworking had spread to the southeastern tip of the continent, with sites such as Matola in Mozambique and ‘Silver Leaves’ in South Africa being dated to between the 1st-2nd century CE.14 While few studies have been conducted in the northern Horn of Africa, there’s evidence for extensive use of iron tools at Beta Giogyis and Aksum in Ethiopia, between the late 1st millennium BC and the early centuries of the common era. 15
While proponents of an independent origin of iron technology in Africa rely on archeological evidence, the diffusionist camp is driven by the hypothesis that ironworking required pre-existing knowledge of copper smelting, they therefore surmise that it originated from Carthage or Meroe. However, there's still no material evidence for any transmission of ironworking technology based on the furnace types from either region16, and the recently confirmed dates from Cameroon, Central Africa, and Senegal significantly predate those from Meroe, the Fezzan, and Carthage.17
Furthermore, there was no contact between the earliest West African Iron Age sites of the Nok Culture with North Africa; nor was there contact between Nok and its northern neighbor; the Gagijana culture of Lake Chad (1800-400BCE) which had no iron at its main proto-urban capital of Zilum;18 nor were there links between Carthage and Zilum during this period. Even links between more proximate regions like the Fezzan in Libya (which had Iron by 500 BCE) and the Lake Chad basin before the common era remain unproven.19
The site of Oboui in the Central African republic has been the subject of intense interest by archeometallurgists since it provides the earliest known iron-working facility anywhere in the world.
So while it may "never be possible to write a history of African metallurgy that truly satisfies the historian's inordinate greed for both generalization and specificity," the most recent research weighs heavily in favor of an independent origin of Ironworking in Africa.
1st millennium BC Nok furnace site at Janjala, Nigeria.
The process of Smelting and Smithing Iron in African furnaces.
The process of ironworking starts with the search and acquisition of iron ores through mining and collecting, followed by the preparation of raw materials including charcoal, followed by the building of the smelting installations, furnaces, tuyeres and crucibles, followed by the smelting itself which reduces the ores to metal, followed by bloom cleaning, smithing, and the forging of the finished product20. This was extremely labour-intensive and time-consuming, especially collecting the ore and fuel, which could at times last several weeks or months.21
In nature, iron may be found in five different compounds: oxide, hydroxide, carbide, sulfide, and silicate, of which there are many different types of iron ores in Africa (lateritic, oolitic, magnetite-ilmenite, etc) which invariably influenced the smelting technology used. Ancient African bloomery furnaces exhibit remarkable diversity, suggesting constant improvisation and innovations. As one metallurgist observed, "every conceivable method of iron production seems to have been employed in Africa, some of it quite unbelievable." African ironworkers adapted bloomery furnaces to an extraordinary range of iron ores, some of which cannot be used by modern blast furnaces and weren’t found anywhere else in the Old World.22
African iron-smelting processes are all variants of the bloomery process, in which the air blast must be stopped periodically to remove the masses of metal (blooms), while the waste product (slag) may be tapped from the furnaces as a liquid, or may solidify within it. Most of the oldest African furnaces were shaft furnaces that ranged from small pit furnaces to massive Natural-draft smelting furnaces with tall shafts upto 7 meters high.23
Natural draft furnaces in the Seno plain below Segue, Burkina Faso, 1957, Quai Branly. Earthen smelting furnaces in Ouahigouya, near the capital of Yatenga kingdom, Burkina Faso, 1911, Quai Branly.
Examples of African bloomery furnace types (by F. Bandama), Approximate distribution of bowl, shaft, and natural draught furnace types in Africa. (by S. Chirikure).
Bloomery smelting operates around 1200°C; ie at a temperature below the melting point of iron (1540°C), which is high enough only to melt the gangue minerals in the ore and separate them from the unmolten iron oxides. Air is introduced to the furnace either through forced draft using bellows and tuyères (ceramic pipes), or by natural draft taking advantage of prevailing winds or utilizing the chimney effect. This enables the fuel (usually charcoal) to burn, producing carbon monoxide, which reacts with the iron oxide, ultimately reducing it to form metallic iron.24
These furnaces could produce cast iron and wrought iron, as well as steel, the latter of which there is sufficient evidence in several societies, most notably in the 18th-century kingdom of Yatenga between Mali and Burkina Faso, where blacksmiths built massive furnaces upto 8m high to produce steel bars and composite tools with steel-cutting edges25. Steel is iron alloyed with between 0.2% and 2% carbon, and it has been found in archaeometallurgical studies of furnaces and slag from Buhaya in northern Tanzania,26 and in northern Mandara region of Cameroon among other sites.27 Most high-carbon steel could be produced directly in the bloomery furnace by increasing the carbon content of the bloom, rather than by subsequent smithing as in most parts of the Old World.28
Iron smelting at Oumalokho near the border of Mali & Cote d’ivoire, illustration by Louis Binger, ca. 1892
steel sword with gold hilt, blade decorated with incised geometric and floral decoration, ca. 1900, Asante, Ghana, V&A museum
Once smelting was complete, the bloom settled to the bottom of the furnace and was removed for further refinement through repeated heating and hammering into bars using large hammerstones. After which, the iron bars produced from this process were forged at high temperatures, and the blacksmith will use various hammers, tongs, quenching bowls, and anvils to work the iron into a desired shape. In a few cases, methods like lost wax casting and the use of molds which were common in the working of gold and copper alloys were also used for iron to produce different objects, ornaments, and ingots.29
Like all forms of technology, the working of Iron in Africa was socially mediated. The role of blacksmiths was considered important but their social position was rather ambiguous and varied. Depending on the society and era, they were both respected or feared, powerful or marginalized, because they wielded social power derived from access to knowledge of metallurgy, divination, peacemaking, and other salient social practices30.
The smith’s craft extended from the production of the most basic of domestic tools to the creation of a corpus of inventive, diverse, and technically sophisticated vehicles of social and spiritual power The various taboos and rituals associated with the craft were a technology of practice that enabled smelters to take control of the process through learned behavior.31
One key feature of African metallurgy is that it resists homogenization, yet anthropologists who study the subject are more inclined to homogenize than to seek variations. In contrast to the making of pottery and sculptures, the apprenticeship of iron smelting has not been the focus of ethnological studies. While such studies can only provide us with information from the 20th century, the persistence of pre-industrial methods of iron production in some parts of the continent suggests that some of this information can be extrapolated back to earlier periods.
A number of researchers have left ethnographic descriptions of smelting sessions that they attended, observing that there is a head smelter or an elder’s council, as well as young people or apprentices. Under the leadership of a master, the metallurgists seem to take part collectively in the smelting, and the associated rituals involved in the process. Each member of a smelting session detects the physical and chemical changes of the material being processed inside the furnace.32
Ethnographic descriptions show the major importance of smith castes and ritual practice, as well as political control over resources like iron ore, wood, land, and labour.33 In many parts of the continent, there's extensive evidence that iron smelting was considered ritually akin to the act of procreation and therefore was carried out away from or in seclusion from women and domestic contexts34. Yet there were numerous exceptions in southern and East Africa where women were allowed in the smelting area, procuring iron ores, and constructing furnaces.35
Evidently, all available labour was utilized for iron working when necessary, depending on the cultural practices of a given society.
The role of Iron in early African Agriculture and Trade.
Ironworking played a pivotal role in the advent and evolution of agriculture and long-distance trade across the African continent, as the widespread use of iron tools helped to increase food production and the exchanges of surpluses between different groups. In many societies, the various types of iron tools (such as plows and hoes) the design of furnaces, and the organization of labor, influenced and were influenced by developments in agriculture, trade, and cultural exchanges.36
For example, the use of natural draught furnaces and the creation of a caste of blacksmiths frees up labour for working the raw iron to make iron objects and develop long-distance trade and exchange. Such furnaces high fuel-low labour furnaces were particularly common in the West African Sudanic woodland zone from Senegal to Nigeria and in the miombo woodlands of Tanzania, Zambia, Malawi and Mozambique, where labour requirements for swidden agriculture may have reduced available labour for smithing.
Natural draft furnaces; Yeke, D.R.Congo, early 20th century, Royal Museum for Central Africa. Aushi, Zambia, early 20th century, British Museum. ‘A Bafipa natural draft furnace in Tanzania’, photo by S.T.Childs.
In other regions, the demand for Iron objects beyond the immediate society in which specialist smiths lived facilitated the production of large quantities of Iron for export. For example, at least 15 sites used by Dogon smiths in south-central Mali produced a about 400,000 tonnes of slag – or 40,000 tonnes of iron objects over a period of 1,400 years, about 26 tones of iron objects per year while the site of Korsimoro (Burkina Faso) yielded 200,000 tonnes of slag - or 20,000 tonnes of iron objects between 1000-1500 CE, about 32 tonnes of iron per year.38
This scale of production doubtlessly suggests that the iron was intended for export to neighboring societies, albeit not at a scale associated with large states. For example, the dramatic rise in iron production from a small site of Bandjeli in Togo, from less than a tonne in the 18th century to over 14 tones per year by 1900 may have been associated with demand from sections of the kingdoms of Dagomba, Gonja, Mamprusi, although it was far from the only site39. It therefore appears that in most parts of Africa, specialization was based on pooling together surplus from various relatively small-scale industries which cumulatively produced bigger output, and may not have been concentrated even in the case of large states.40
Several types of iron objects served as convenient stores of value and were at times used as secondary currencies in some contexts, primarily because of the ever-present demand for domestic and agricultural iron implements like hoes, knives, machetes, harpoons, as well as the general use of metals for tribute, social ceremonies, and trade.41
In West Africa, iron blooms were traded and kept as heirlooms, while knives and iron hoes were both a trade item and a medium of exchange in parts of Southern Africa and west-central Africa42. In East Africa, where long-distance traders like the 19th century Swahili traveler Mwenyi Chande were required by local rulers to give iron hoes as a form of tax on their return journeys from the interior as a substitute for cowries and cloth. Similary In Ethiopia, iron plowshares were valued items of trade.
Illustration depicting an ‘Abyssinian Plough’. ca. 1868, Library of Congress.
Iron in the History of Warfare and Politics in Pre-colonial Africa.
Given its centrality in agriculture and trade, the spread of iron working in Africa was closely associated with the emergence and growth of complex societies across the continent.
The rise of African states resulted in an increased demand for symbols of prestige and power, among which iron, copper, and gold were prominent. Increase in metal production and changes in furnace construction in the Great Lakes region for example, were associated with the emergence of the kingdoms of Bunyoro, Buganda, and Nyiginya (Rwanda),44 and similar developments in southern Africa and the East African coast were associated with the rise of the kingdoms at Great Zimbabwe and Kilwa.45
A significant number of iron tools found at the oldest sites of ironworking across the continent included knives and arrowheads. Additionally, a number of historical traditions of societies in central Africa like the kingdom of Ndongo and Luba, either attribute or closely associate the founding of kingdoms to iron-wielding warrior-kings and blacksmiths46. Iron was often conceptually integrated within the organizing structures of these states, with iron symbolism frequently incorporated within iconography, mythology, and systems of tribute payment, all of which underscores the importance of iron weapons to the emergence and expansion of African kingdoms and empires, especially in warfare.
Sword made by a Ngala smith from Congo, Copper alloy handle with iron struts attached to iron blade, Late 19th century, Saint Louis art museum
Iron Sword, 19th century, Asante Kingdom, Ghana, British Museum
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