This article concerns a series of 20 samples submitted for AMS radiocarbon dating from historic sites in the Libyan Sahara. The sites had been identified initially from remote sensing analysis, then visited on the ground in 2011 and organic samples suitable for a dating programme obtained. With the help of an award from the NERC-AHRC National Radiocarbon Facility, this initial suite of dates has been provided. The results are important in several ways. They demonstrate very clearly that settlement in this hyper-arid desert landscape reached its densest pattern in the late Garamantian era, broadly the fourth-fifth centuries AD. In the Islamic era that followed, though the overall population appears less dense, our dates throw light on several possible phases of settlement renewal.