This territorial union may be caused by foreign influences. It may be that stronger hordes have crowded the herdsmen forward, or that their increase in population has reached the limit set by the nutritive capacity of the steppes or prairies; it may be that a great cattle plague has forced the herdsmen to exchange the unlimited scope of the prairies for the narrows of some river valley. In general, however, internal causes alone suffice to bring it about that the herdsmen stay in the neighborhood of their peasants. The duty of protecting their tributaries against other “bears” forces them to keep a levy of young warriors in the neighborhood of their subjects; and this is at the same time an excellent measure of defense since it prevents the peasants from giving way to a desire to break their bonds, or to let some other herdsmen become their overlords. This latter occurrence is by no means rare, since, if tradition is correct, it is the means whereby the sons of Rurik came to Russia. As yet the local juxtaposition does not mean a state community in its narrowest sense; that is to say, a unital organization. In case the herdsmen are dealing with utterly unwarlike subjects, they carry on their nomad life, peaceably wandering up and down and herding their cattle among their perioike and helots. This is the case with the light-colored Wahuma,[32] “the handsomest men of the world” (Kandt), in Central Africa, or the Tuareg clan of the Hadanara of the Asgars, “who have taken up their seats among the Imrad and have become wandering freebooters. These Imrad are the serving class of the Asgars, who live on them, although the Imrad could put into the field ten times as many warriors; the situation is analogous to that of the Spartans in relation to their Helots.”[33] The same may be said of the Teda among the neighboring Borku: “Just as the land is divided into a semi-desert supporting the nomads, and gardens with date groves, so the population is divided between nomads and settled folk. Although about equal in number, ten to twelve thousand altogether, it goes without saying that these latter are subject to the others.”[34] And the same applies to the entire group of herdsmen known as the Galla Masi and Wahuma. “Although differences in possessions are considerable, they have few slaves, as a serving class. These are represented by peoples of a lower caste, who live separate and apart from them. It is herdsmanship which is the basis of the family, of the state, and along with these of the principle of political evolution. In this wide territory, between Scehoa and its southernmost boundaries, on the one hand, and Zanzibar on the other, there is found no strong political power, in spite of the highly developed social articulation.”[35]