130 borders and frontiers: The Americas larger during the medieval period Around its shores numerous peoples settled, each practicing a unique way of life Some were farmers, others herders, and still others fishermen The borders that divided these various peoples were ill defined In time tensions emerged, and each community began to develop governmental and economic structures that perhaps conflicted with those of its neighbors Because of their central locations as links in east–west and north–south trade routes, at least two of the Lake Chad peoples achieved dominance These were the Kanem on the northeast side of the lake and the Bornu on the southwest Between roughly 750 and 1600 a complex series of political events took place that continually reshaped the region and redefined its borders Some of these events involved the arrival of Islam Others involved various power struggles between the peoples who lived in the vicinity of Lake Chad The chief event, though, was the desire of the Kanem to expand their borders and introduce Islam to their neighbors To this, they had to forge a strong military To fund military enterprises, the Kanem needed a stable source of wealth To this end they allied themselves with farming societies such as the Bornu, rather than with nomadic pastoralists, who were less reliable as sources of wealth However, the Kanem were never able to carry out fully their plans for dominating the region Nearby rival dynasties of kings opposed them, and Kanem was never able to accumulate the wealth necessary to achieve dominance In response to numerous crises the Kanem simply picked up and moved to Bornu in the late 13th century By the middle of the 14th century and throughout the 15th, the kingdom of Bornu became yet another dominant empire in western central Africa after having entirely redefined its borders The kingdoms of Mali, Songhai, Hausaland, and KanemBornu dominated from West Africa to the continent’s interior Throughout southern Africa the Bantu migration continued until roughly 1000 Bantu, which means “the people,” is a catchall word that refers to the many peoples who inhabited such regions as Nigeria and Zambia, eventually making their way to Zimbabwe and South Africa The earliest Bantu peoples began to spread through Africa in phases beginning in about the second millennium b.c.e Historians regard the third phase of the Bantu migration as having begun at the start of the Common Era and continuing to about 1000, when the Bantus reached the southernmost parts of Africa Bantu refers less to an empire or kingdom, however, than to an ethnic group, united primarily by descent from a common language group The importance of the ongoing Bantu migration until well into the medieval period is that it demonstrates that the formation of nation-states was a continuing process, with new nations (for example, Zimba- bwe) formed and borders adjusted in response to the mass movements of peoples, often in response to war and climatic change It should be noted that although the Bantu still exist as an ethnic group, the term in South Africa is regarded as pejorative because it was the word used by the South African apartheid regime The Americas by J J George The period from 500 to 1500 saw great change throughout the Americas with respect to borders and frontiers Political boundaries in the modern sense of a negotiated contract indicating a fixed extent were rarely, if ever, noted; generally speaking, the literature talks about zones, spheres, and areas rather than strict borders and lines drawn from one point to another point Many factors, including population growth and expanding cities, city-states, and empires, led to changing territorial demands that were reflected, in turn, by shifting borders and frontiers The situation was somewhat different in the later years of the period, which saw the rise of dramatic new examples of empire with the Aztec in central Mexico and the Inca in Andean South America With empires came new manners of social, political, and economic organization combined with thoroughness in warfare that again redefined what a border or frontier meant The term frontier often is reserved in the American lexicon for understanding the westward expansion of the United States as a manifest impulse through wide-open, uninhabited territory, even though long-established cultures had been in residence for many hundreds—in some cases, thousands— of years As used by modern political geographers, frontier generally designates a physical margin, fringe, or outer boundary—more of a zone than a line—dividing peoples or cultures It is also the division between settled and uninhabited parts of one nation, state, or culture area The whole of the Americas provided many different examples of cultural patterns, from nomads to hunter-gatherers and from small early agrarian settlements to mammoth empire systems, though populations remained relatively small compared with the total landmass, especially in North America, and often a substantial frontier existed between contemporaneous cultures or peoples Inevitably, however, those cultures came into contact Conflict, warfare, tribute, or diplomacy were then common means of resolving or settling whatever political objective the parties held, and certainly this meant that thresholds, like borders, were challenged Border in a modernist sense symbolizes aspects of nationhood and identity construction that are linked to state building Factors that ultimately define borders include natural