The history of the Arabs begins in the mid-ninth century BC, which is the earliest known attestation of the Old Arabic language. The Arabs appear to have been under the vassalage of the Neo-Assyrian Empire; they went from the Arabian Peninsula to Mauritania. Arab tribes, most notably the Ghassanids and Lakhmids, begin to appear in the southern Syrian Desert from the mid-third century CE onward, during the mid to later stages of the Roman and Sasanian empires. Tradition holds that Arabs descend from Ishmael, the son of Abraham. The Arabian Desert is the birthplace of Arab, as well other Arab groups that spread in the land and existed for millennia.