They indicate that on the eve of the second millennium communities deep in the rainforest belt were indirectly linked with avenues of trans-Saharan trade, receiving beads that came from distant towns in Africa or beyond.4
MAP 1.1 Places mentioned in chapter 1. Map by Brian Edward Balsley, GISP.
This material evidence also presents visually dazzling corroboration of the rather cursory references to trade beads in the Arabic-language written sources. There is, however, an important caveat: the beads themselves are of only limited use in identifying specifically where they came from. Red beads made of carnelian, for example, which were found at both Igbo Ukwu and Gao, might have been from Gao itself or, alternatively, from other known supply centers as far away as Egypt or India. Monochrome glass beads found in those same sites and others could have been from Morocco, Egypt, or the Near East, which were the major known suppliers of such beads between the twelfth and fifteenth centuries.5 Whatever their precise origins, however, beads from these early archaeological sites are important historical sources for understanding West Africa as a socially diverse zone of bead connoisseurship that persisted into and during the era of Atlantic trade with Europeans.
Commercial exchanges depended on various forms of West African currencies—what they were, how they were valued, and specifically where and how they circulated. It is important to note that during the centuries of trans-Saharan trade, West African merchants did not adopt coinage from North Africa as a general form of currency south of the desert, although limited numbers of gold dinars and silver dirhams did at times circulate in some cities and towns. Instead, they continued to use commodity currencies, the major West African ones being gold dust, rock salt, cotton textiles, bar iron, and sea salt, along with cowry shells from the Indian Ocean. These items served as general-purpose currencies largely because demand for them was widespread, steady, and consistently high. They were important as trade goods and also functioned as money, being used as a medium of exchange, as a store of value, and as units of account in valuation and pricing. Each had its own history. Some were products rooted in local natural resource endowments, and some were the products of far-off contacts and cultural influences arising out of long-standing ties with the wider Islamic world. Sufficiently detailed histories of these currencies are not yet possible owing to the very limited written and archaeological sources for documenting them, but there is no doubt that they worked together over time as a flexible, fluctuating, and interlocking system of currency flows across West Africa’s geographical and linguistically rich social landscape.
The largest regional currency zone, extending over much of the West African interior, owed its existence to the importance of the trans-Saharan caravan trade. In this zone people reckoned prices and exchanged goods based on units of African gold, imported cowry shells, and Saharan rock salt. The other three currencies—cotton textiles, bar iron, and sea salt—circulated in and between smaller subregions and also into and out of Muslim trading networks. Sea salt produced along the coast was regularly sought out by inland merchants, especially those who had ready access to the strips of woven cotton cloth that artisans in the savanna and Sahel zones produced for export. Salt producers on the coast, for their part, preferred to bargain for cotton textiles, which were also accepted in exchange for gold in gold-producing areas and for captive humans in other places. Blacksmiths with access to locally smelted iron, either directly or by trade, worked it out into standard-sized units that Europeans called “bar iron,” which then circulated as local and regional currencies in markets across West Africa.6
Combining the known production centers and circulation zones of these commodity currencies and plotting them on a map of West Africa presents a useful summary overview of the complexity of trade and commerce there ca. 1500. Map 1.2 includes the richest goldfields and Saharan rock-salt deposits, the central zone of cowry circulation, and major production centers of bar iron and cotton textiles for export. Coastal sea salt–producing areas were many and changing and so are not individually shown. In addition, the map shows prominent supply areas of kola nuts, mainly because of their importance in linking the forest zones where they grew to consumer markets for them in the savanna and Sahel regions. There they were of great cultural and social value—as well as being a source of caffeine—and served as a respectable welcoming gift among many peoples, Muslims and polytheists alike. However, since they were perishable and therefore difficult to store for very long, they were a consumer product and not, strictly speaking, a major currency-like store of value. The map also includes areas of copper extraction, but the volume of production and circulation of local copper was relatively limited, thus setting up a significant opportunity for European importers of the metal and its alloys, brass and bronze. The basic spatial organization and material logic of West Africa’s trading networks shown in the map allows for a sharper recognition and appreciation of Africa’s participation in early modern Atlantic trade.
MAP 1.2 Production and circulation of commodity currencies in West Africa, ca. 1500. Map by Brian Edward Balsley, GISP.
Of the six major commodity currencies, iron was probably the oldest. Early evidence for smelting iron ore comes from archaeological sites in what is now Senegal, Niger, Nigeria, and Cameroon, all of them roughly dating to the sixth century BCE. For the upper Niger River valley in what is now Mali, evidence of iron working dates from the earliest occupation of a major town in the region, Jenne-jeno, in the third century BCE. Especially intriguing is the fact that smelting iron ore and forging it into useful implements and symbols of prestige were being carried out in locations that were some distance from both the ore deposits and the special hardwood trees necessary for making the charcoal that fueled the region’s furnaces and forges. Such a complex spatial organization of the several components of iron production suggests a divided and specialized labor force that, for unknown reasons, had invested in these added costs of transport.7 If and when a bar iron currency was adopted there is not presently known. Similarly, little is known specifically about the subsequent transfers of iron technology to other locales and workers, but it can be inferred that the knowledge and skills traveled local, regional, and interregional trade routes alongside iron products and other goods. As the southerly extension of trans-Saharan trade took on greater significance and intensity after the seventh century CE, it is likely that smelters and smiths would have become more productive and diversified their iron wares with the increasing connections to new markets.
Then, in the second millennium, two gradual historical changes began that reshaped the human geography of West Africa and also the contours of its trading networks. One was a drier climate that prompted large scale southerly demographic movements and concentrations of people in new towns and settlements. The other was an expansion and intensification of Muslim trade across the Sahara, which increased the number of Muslims—both immigrants and local converts—among the populations of sub-Saharan Africa. These economic and cultural transformations led, in turn, to new sources and greater supplies of commodity currencies and more widespread circulation of them.
Climatic change brought transfers of iron technology into new geographical areas and communities. A dry period, lasting from ca. 1100 to ca. 1500, extended the reach of the Sahara’s southern “shore,” driving people southward in search of rainfall adequate for farming. Among them were iron smelters and smiths. By the end of the period, important new iron production centers had arisen in the Futa Jallon massif and the Konyan highlands, both of them mountainous areas that lay on the timber-rich forest edge in the hinterland of the Upper Guinea Coast.8 Even though accessible surface deposits of iron ore were not unusual in West Africa and could be exploited in many locales on small scales, by the sixteenth century these two places in particular became major producers and exporters of bar iron.9
Standard units of bar iron currency usually took the form of semifinished tools or implements that were useful in land clearance, farming, hunting, or war, as well as being widely recognized units of value. Unfortunately, however, there is little to go by in knowing specifically what some of the earliest forms of bar iron were like. They remain obscure because metallic iron tends not to survive in the