Humans have inhabited the Arabian Desert since early Pleistocene times (i.e., about 2.6 million years ago). Artifacts have been found widely, including at Neolithic sites in Qatar and Dubai, but they are most abundant in the southwestern RubĘż al-Khali. Archaeological research sponsored by the Saudi government has uncovered many Paleolithic sites. Remains of cultures from the past 3,000 years occur in many parts of the peninsula.