Rain in the desert woodland-savannas is often scarce (50-200 mm [2-8 in] per year) and highly erratic. These ecosystems are found in northern Africa rimming the Sahara Desert and in southwestern Africa bordering the Namib-Kaokoveld Deserts. All areas are daunted by overhunting and poaching of native large ungulates, to the point that many endemic species no longer exist in these regions. The xeric montane regions of the eastern Sahara Desert, Tibesti and Jebel Uweinat, were strategic staging areas in the North African desert operations of British and Italian troops before and during World War 2. The areas provide semi-perennial water supplies (wadis), which historically served as stopping points for slave caravans, nomads and traders. The area is currently inhabited by nomadic pastoralists with population densities as low as 0-1 people per kilometer squared. In the Namibian savanna-woodlands rain is most common in the summer, and the winter season is approximately 90 days with potential for light frosts.