Once a pastoral society evolves beyond clan- and lineage-based organization, it must develop more elaborate hierarchical structures. Khazanov (1984: 228 ff.) reviews the many theories of the evolution of the State among nomads, which was once a subject of much scholarly debate and the source of many improbable historical typologies. Powerful and extensive States were most common in Asia, where the links between pastoralism and warfare were well-developed and there was the potential to accumulate enormous storable wealth. In subarctic areas and the semi-arid pastoral zones of Africa, the inability to store wealth other than livestock, and the difficulties of keeping horses (the pre-eminent raiders' animal) alive meant that the large-scale kingdoms that were typical of the steppes did not develop. The accounts of visitors to the courts of the Khans underline the enormous wealth and sophistication that they had accumulated over time and the ferocious means that such rulers employed to maintain their authority intact. The Mongol Empire once stretched from the shores of the Pacific to Poland, a land empire larger than any other in history (Jagchi and Hyer, 1979). It would probably be inappropriate to link the Inca State to the use of llamas in vertical transhumance; similar systems in the Alps of Europe are historically associated with democratic tendencies.
Nonetheless, a correlated feature of such empires was their inherent instability. Despite the effective warfare techniques and rapid evolution of the Mongol Empire, its failure to settle the furthest areas of its conquest meant that they soon shook themselves free of their new rulers. Long lines of communication and mobile armies made dissent and secession all too easy, and only by settling - and essentially discarding nomadism - was it possible to form a more permanent political institution (Barfield, 1989).
In West Africa, the Fulše cattle nomads in the Sahelian region began a jihad in 1804, conquering the seven original Hausa kingdoms of today's northern Nigeria and pushing eastwards to today's northern Cameroon. They settled as rulers of the kingdoms they conquered, dispensed with their cattle and, in most cases, switched to the language of the peoples of their empire. Meanwhile, their "brothers", who still herded cattle, migrated still further into Central Africa, impelled onwards by ever-increasing arable expansion.
With their military traditions and high mobility, pastoralists have not historically been loyal subjects of nation States. For the same reason, the States that they founded tended to be short-lived. This did not cause particular problems until the twentieth century, when national borders began to play a key role in worldwide geopolitics and the free movement of livestock started to be seen as a security and health threat, on the one hand, and as a potential loss of national wealth, on the other. Many West African States, although they depend on the meat and milk that pastoralists produce and benefit from the latters' opportunistic attitudes to national borders, condemn herders for not staying within a confined range (Blench, 1996). Throughout Central Asia many pastoral peoples have been split by the establishment of States with heavily defended borders (see e.g. Tavakolian, 1984). Unlike their counterparts in Africa, where pastoral peoples move around relatively freely in open, arid spaces, Asian peoples such as the Kazakhs and the Mongols have been divided by States that have highly varied policies. Moreover, sensitive border areas have generally been closed to outsiders, so information on pastoral societies in these regions has been tightly controlled.
