During the previous field seasons (2011-2015), the aim has been to provide a comprehensive view of the evolution of regional occupation from the Palaeolithic to the Islamic era. This has been achieved through the creation of archaeological and geomorphological maps of the oasis, the study of significant sites: AK-22, AK-31 (Palaeolithic); ʿAyn al-Ḍilaʿ, Umm al-Shaʿal (protohistoric necropolis), and al-Yamāma (Late Pre-Islamic / Early Islamic settlement); and environmental studies (geomorphology, sedimentology, palynology, anthracology and faunal remains) in the site of al-Yamāma and on the palaeolake of al-Hayāthim. The fifth season resumed the exploration of two of these sites: ʿAyn al-Ḍilaʿ (protohistoric necropolis) and al-Yamāma (Late Pre-Islamic / Early Islamic settlement), the aim being: - To start the excavation of tapered structures and tumuli south of the protohistoric necropolise at ʿAyn al-Ḍilaʿ : 8 dry-stone graves ascribed to the Bronze and Iron age have been excavated on the north-western edge of the limestone plateau of Jabal al-Qusayʿa, at ʿAyn al-Ḍilaʿ. - To continue the excavation at al-Yamāma in areas N6 (the mosque and its surrounding) and G17 (pottery workshop) : The excavation of the dwelling area west of the mosque partly unearthed during the fourth season was resumed and achieved: enlargment of Trench D, soundging under the Islamic occupation, uncovering of pre-Islamic dwellings. To the south of the site (area G17), Sounding 3 initiated in 2012 was resumed and widened. - To realize the architectural study of the Great Mosque (Building 1) at al-Yamāma (area N6) : It revealed at least 5 architectural phases each corresponding to a different mosque superimposed one above the other, from the Umayyad/Abbasid period until the 18th century.