Nuer living to the east of the Nile speak of their western relatives as "homeland Nuer" and have a consistent oral tradition indicating that their expansion across the Nile, as far as the Ethiopian border, has a 200-year legacy. In the process of this expansion, they forced the Anuak to migrate farther east into Ethiopia, and incorporated many Dinka into Nuer communities. Nuer versed in such matters suggest that at one time three "brothers"—Nuer, Dinka, and Atuot—once lived in a neighboring territory. Legends suggest that they parted company to go their own ways following a dispute about the rightful ownership of a number of cattle. Both Atuot and Nuer traditions indicate that this separation and initial migration originated in a cattle camp in what is now termed western "Nuerland." These legends of migration sometimes have mythical properties, but it is prudent to appreciate them also for their historical character. It is certain that the Nuer, Dinka, and Atuot have a common "origin," and archaeological research may indicate that the spread of domesticated cattle in this region of Africa was contemporaneous with the origin of distinct ethnic identities. An especially active period of Nuer eastward migration began in the middle of the nineteenth century. Beginning at the turn of the twentieth century, British colonial policy in Nuerland was aimed at fixing boundaries between the Nuer and the Dinka, thus effectively halting a dynamic process of cultural change that had been unfolding for centuries.