The Earth and Its Peoples AP 5th Edition - Mongol Eurasia and Its Aftermath, 1200–1500 - Chapter 12
I. The Rise of the Mongols, 1200?1260 A. Nomadism in Central and Inner Asia 1. Nomadic groups depended on scarce water and pasture resources; in times of scarcity, conflicts occurred, resulting in the extermination of smaller groups and in the formation of alliances and out-migration. Around the year 1000, the lands inhabited by the Mongols experienced unusually dry weather, with its attendant effects on the availability of resources and pressures on the nomadic Mongol tribes.