with surveys conducted by "A. Pomel (1893-1898), Stéphane Gsell (1901-1927), G. B. M. Flamand (1892-1921), Leo Frobenius and Hugo Obermaier (1925), Henri Breuil (1931-1957), L. Joleaud (1918-1938), and Raymond Vaufrey (1935-1955)." Tassili was already well known by the early 20th century, but Westerners were broadly introduced to it through a series of sketches made by French legionnaires, particularly Lieutenant Charles Brenans in the 1930s. He brought with him French archaeologist Henri Lhote, who would later return during 1956 - 1957, 1959, 1962, and 1970. Lhote's expeditions have been heavily criticized, with his team accused of faking images and of damaging paintings in brightening them for tracing and photography, which resulted in reducing the original colors beyond repair. Current archaeological interpretation The site of Tassili was primarily occupied during the Neolithic period by transhumant pastoralist groups whose lifestyle benefited both humans and livestock. The local geography, elevation, and natural resources were optimal conditions for dry-season camping of small groups. The wadis within the mountain range functioned as corridors between the rocky highlands and the sandy lowlands. The highlands have archaeological evidence of occupation dating from 5500 to 1500 BCE, while the lowlands have stone tumuli and hearths dating between 6000 to 4000 BCE. The lowland locations appear to have been used as living sites, specifically during the rainy season. There are numerous rock shelters within the sandstone forests, strewn with Neolithic artifacts including ceramic pots and potsherds, lithic arrowheads, bowls and grinders, beads, and jewelry. The transition to pastoralism following the African Humid period during the early Holocene is reflected in Tassili n'Ajjer's archaeological material record, rock art, and zooarchaeology. Further, the occupation of Tassili is part of a larger movement and climate shift within the Central Sahara. Paleoclimatic and paleoenvironment studies started in the Central Sahara around 14,000 BP and then proceeded by an arid period that resulted in narrow ecological niches. However, the climate was not consistent and the Sahara was split between the arid lowlands and the humid highlands. Archaeological excavations confirm that human occupation, in the form of hunter-gather groups, occurred between 10,000 and 7,500 BP; following 7,500 BP, humans began to organize into pastoral groups in response to the increasingly unpredictable climate. There was a dry period from 7900 and 7200 BP in Tassili that preceded the appearance of the first pastoral groups, which is consistent with other parts of the Saharan-Sahelian belt. The pre-Pastoral pottery