Whether some parts of the desert such as highlands like the Red Sea Hills were reached by the westerlies or weather systems associated with the subtropical jet stream—and thus received precipitation—is contentious. It is only clearly supported for the Maghreb in northwestern Africa, though river flow/terrace formation and lake development in the Tibesti and Jebel Marra mountains and residual Nile flow may be explained in this way. The highlands of Africa appear to have been less affected by drought during the last glacial maximum.