Climate and geography have significantly impacted African society. The continent has extensive deserts like the Sahara which cover most of the land area. Environmental challenges like desertification and lack of arable land have caused groups like the Bantu to migrate within Africa over thousands of years in search of resources. The geography, which includes the Great Rift Valley and grassy savannas, has also influenced where human settlements could be sustained through farming and herding. More recently, European colonialism disrupted many African societies and drew boundaries without regard for ethnic groups, contributing to ongoing conflicts over land and resources.