Unlike their Byzantine and Sassanid predecessors, who simply sought to contain the steppe peoples through fortifications and political alliances, the Arabs were "expansionists interested in conquest". From the beginning, they actively pursued a northward expansion, quickly posing a direct threat to the survival of the Khazars as an independent polity. The Khazars, on the other hand, followed a strategy common to their nomadic predecessors: while raids might reach deep into Transcaucasia, and even into Mesopotamia and Anatolia, they were not aimed at conquest, but rather "typical of nomads testing the defenses of their sedentary neighbors", as well as a means of gathering booty, the acquisition and distribution of which was fundamental to the maintenance of tribal coalitions. For the Khazars, the strategic stake of the conflict was control of the passes of the Caucasus.