The border consists of a series of mostly straight lines. The northern section of the boundary begins near the Tibesti Mountains at the Libyan tripoint and proceeds roughly south-eastwards; the border here cuts across the Massif d'Afafi and the Erg of Bilma. The middle section of the boundary slants to the south-west slightly, with the southern section continuing in a much more pronounced south-westerly direction down to Lake Chad, whereupon a straight line veering to the south-east connects the border to the Nigerian tripoint. The majority of border lies within the Sahara Desert, with the more southerly sections lying within the Sahel. The border region is very sparsely populated, there being no towns or villages in its immediate vicinity.