The African ancestors of the Berber people are assumed to have spread into the area by the Late Bronze Age. The earliest known name of such a tribe is that of the Garamantes, who were based in Germa, southern Libya. The Garamantes were a Saharan people of Berber origin who used an elaborate underground irrigation system; they were probably present as tribal people in the Fezzan by about 1000 BCE, and were a local power in the Sahara between 500 BCE and 500 CE. By the time of contact with the Phoenicians, the first of the Semitic civilizations to arrive in Libya from the East, the Lebu, Garamantes, Berbers and other tribes that lived in the Sahara were already well established.