borders and frontiers: Africa 129 Sandstone frieze from the first cathedral at Faras (Sudan, seventh century); in the sixth century the three Nubian kingdoms, known as the kingdoms of Nobatia, were converted to Christianity and were ruled from Faras, just inside the modern northern border. (© The Trustees of the British Museum) and rebellion, led to the collapse of the Mali Empire by about the end of the 16th century One example of the inability of medieval African states to maintain stable borders is provided by the emergence of the Songhai The history of the Songhai peoples is shrouded in mystery, and scholars continue to debate the details based on written and oral histories One point of agreement, however, is that the Songhai coalesced as a society in roughly 1000 They were probably not indigenous to the Niger River region, but in time they came to occupy an area at the eastern edge of the Mali Empire and were, in fact, a part of that empire Their capital city was Gao, but historians disagree about the city’s location In the early 1400s Songhai broke away from Mali and became an independent empire Thus the emergence of Songhai illustrates the way that borders shifted and were redefined over time as a result of the ongoing movement of peoples throughout the African continent Mali and Songhai are examples of major states that were able to maintain relatively fixed and defined borders for at least some period In this respect they stood in contrast to the nearby kingdom of Hausaland, which occupied the re- gion between the far reaches of the Niger River to the west and Lake Chad to the east beginning in about 1000 Hausaland achieved prominence primarily because its hills were rich in iron ore, so it became a major player in trade that involved iron However, unlike Mali and Songhai, it never developed into an ordered empire with fixed borders Rather it remained a collection of loosely organized city-states, not unlike the city-states of ancient Greece These city-states defended themselves primarily with walled towns Power remained in the hands of local authorities, but the various cities of Hausaland were united by their trading activities Because the kingdom had no fixed borders, its makeup shifted over time as new cities in the region came under the influence of Hausaland and others drifted away This process lasted into the 1300s, when Hausaland’s walled cities came under attack and fell to Islamic invaders The kingdom of Kanem-Bornu illustrates yet another trend in how medieval Africans defined and controlled their borders These people occupied the region around Lake Chad This lake was an immense body of water in the interior of Africa, between the Niger and Nile rivers Although the lake remains one of the largest in the world, it was even