In the Nefud Desert of northern Saudi Arabia, large sandstone outcrops diverted the flow of sand, allowing lakes and marshes to form several times in the past, and evidence has been found for repeated human occupations extending back hundreds of thousands of years.
     The Arabian Peninsula saw some of the earliest human migrations, yet until just five years ago not a single Palaeolithic site had been excavated or dated. Recent excavations in the United Arab Emirates and Yemen have confirmed early human occupations, yet most of the Peninsula remains almost unknown.
     Ancient lakes provide significant evidence for environmental change in Saudi Arabia. There are hundreds, if not thousands, of these lakes. By analysing sediments and associated materials such as fossils, we can draw a detailed picture of the local climate. Few other places on earth saw such dramatic changes, but we have yet to see whether early humans took advantage of broad windows of opportunity in the Early Pleistocene and the earlier part of the Middle Pleistocene.
     In Africa, Homo erectus began to produce hand axes about 1.8 million years ago, in the Acheulean period. In Arabia hand axes are often found at the source of the raw material and adjacent to ancient lakes. The abundance of Late Acheulean material suggests that relatively dense occupations occurred in the later interglacials of the Middle Pleistocene.
     In the East Mediterranean Levant, the transition from the Lower to the Middle Palaeolithic occurs about 250,000 years ago, with an abrupt change in material culture often attributed to population replacement. Though this transition occurs at different times around the world, research in Saudi Arabia suggests that in the north the change happens at the same time as in the Levant. We see significant technological innovations, a shift from handheld tools to hafted tools, and a substantial increase in imported raw materials. However it appears that Middle Palaeolithic occupations were as short-lived as those of earlier periods. In the Middle Palaeolithic (circa 250,000 to 40,000 years ago) there is considerably greater variation in stone-tool technologies.
     The early phases of the Middle Palaeolithic remain poorly understood. The era between about 130,000 to 75,000 years ago has produced a far larger body of finds in Arabia. This is the period when we see evidence for the earliest expansion of Homo sapiens out of Africa and into the Levant, generally regarded as a failed dispersal.
     No archaeological sites are currently known for the period of around 70,000-60,000 years ago. The next wave of human occupation occurred about 60,000 to 55,000 years ago, still associated with a Middle Palaeolithic technology broadly similar to tools produced at this time by Neanderthals in the Levant. The youngest known Middle Palaeolithic assemblages in Arabia, dating to around 40,000 years ago, are found in the United Arab Emirates. There is then a complete absence of human occupation across the Peninsula until the transition to the Holocene, about 12,000 years ago.
     Major debate surrounds the process by which the Neolithic way of life developed in Arabia: was it imported from the Levant, or of indigenous origin? Evidence from stone tools and rock art which date to the earliest phases of this period suggest a bit of both - not simple population dispersal, but rather of some form of cultural diffusion.
     At the remarkable site of Shuwaymis, 'Neolithic' rock art reflects at least two phases. The first is associated with hunter-gatherers, often showing horses, hunting dogs, and human figures with bows. The second shows cattle, but no hunting scenes, and the pastoralists selectively re-engraved some of the earlier hunter-gatherer images. For example, humans were sometimes re-engraved, but the bow and arrows they were holding were not. Along with findings from southern Arabia, this suggests both continuity and change: Arabia was not simply an empty space into which people moved.

Edited from Academia.edu (January 2016)