employment and labor: Africa 387 authority with the power to redistribute agricultural production to specialist labor in other sectors of the economy The state has to be relatively stable and able to support an army for protection and for maintaining open lines of trade and exchange In states like the kingdom of Ghana, rulers instituted taxes on foreign traders who wanted to enter the area These taxes were paid in salt, peacock feathers, iron, silk, and other goods Further, specialists in the economy cannot exercise their crafts without trade and exchange, which provides the raw materials—such as metal, stone, and cotton—that specialists need to create useful goods The most prominent states of medieval sub-Saharan Africa included the kingdoms of Ghana (not to be confused with the modern-day nation of Ghana), Mali, Songhai, and Benin (present-day Nigeria) In 1000 this area had more cities with populations of at least 20,000 people than did any other area of sub-Saharan Africa Two factors contributed to the region’s population density One factor was the area’s abundance of fertile agricultural land A large strip of savanna, running east to west along the southern border of the Sahara Desert, provided high-quality soil for cultivating crops and grassland for grazing herds Accordingly, much of the labor in this region was agricultural The second factor was the presence and extent of trade The region provided a vital link to northern Africa, the Mediterranean, Europe, and trade routes to the East Traders had long been traversing the forbidding Sahara, but the growing prevalence of trading caravans using camel power increased the level of that trade Thus traders from the north were able to cross the desert, arrive at a more hospitable region to the south, and continue around the Horn of Africa to exchange goods This trading enterprise employed a large class of merchants, along with the porters, couriers, and other laborers needed to facilitate the exchange of goods, and numerous marketplaces emerged where goods were bartered Traders also traveled south along the Nile River to the interior of central Africa, though the difficulties of the journey and the lack of a population base the farther south they went limited their efforts Of more significance was the east coast of Africa, where flourishing trade from Asia had taken place in ancient times and continued into the medieval period Little is known about the plant foods available in eastern Africa, but there is ample evidence of considerable economic activity revolving around harvesting the sea and its coasts for fish, shellfish, and turtles Further evidence suggests that the area was home to sizable herds of goats, sheep, and cattle These activities set the economy of the east coast apart from the economies of and the west coast The chief reason for the difference had to with geography The west coast of Africa, with its rocky shorelines, was far less accessible Further, pre- vailing winds from the north made travel by sea difficult on the west coast; it was easy to sail southward, but the return journey was impossible until the development of sails and rudders that allowed sailing against the wind In contrast, the east coast was more accessible, and wind patterns made sea navigation easier A region’s economic activity is largely dependent on the resources available there The region south of the savanna grasslands provides a good example The region is more forested than the savannas, and considerable economic activity was facilitated by the Niger River Agriculture in this region was intensive Evidence suggests that the type of agriculture practiced is what archaeologists call recessional agriculture Crops were planted and grown along floodplains after floodwaters had receded The alluvial silt left behind by receding floodwaters was particularly rich in nutrients and easily worked, so crops could be grown in abundance and surplus grain could be stored and transported All these activities would have employed numerous laborers for planting, cultivating, harvesting, loading, storing, and accounting for produce The produce could be traded to other less-fortunate communities in dryer areas in exchange for crafts and other goods Goods exchanged included salt, cattle, spices, gold, dates, copper, horses, ivory, textiles, animal hides, jasper stone, glass and glass beads, and slaves Important components of the sub-Saharan economy were metallurgy and mining The kingdoms of Ghana, Songhai, and Mali depended heavily on gold, iron, and copper mining Early in the medieval period iron was a dominant metal used to make weapons, tools, and jewelry Most metalwork was done at the household level, and archaeological records abound with evidence of blacksmithing and other activities related to mining or working iron Later gold was a dominant metal, used to forge craft items and as a form of tribute to kings While some mining was organized at the state level, much was conducted at the household level Little archaeological evidence exists to provide information about how the mining industry was organized It is believed that children, because of their smaller stature, were sent into mines to retrieve gold nuggets In Ghana gold nuggets were the property of the king, but individuals were allowed to keep gold dust as a form of income Other important contributors to the economy were pottery and textile workers Pottery was made at the household level and shows a high degree of expertise, not only in the design and firing but also in the painstaking decorations Clay pottery was most common, but metal pots were also prevalent, and the kingdom of Benin was particularly noted for its bronze work Early in the medieval period clothing was made predominantly of leather and animal hides, but by the turn