How did the term Arab change over time?

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.[2] 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.[3] Tradition holds that Arabs descend from Ishmael, the son of Abraham.[4] The Arabian Desert is the birthplace of "Arab",[5] as well other Arab groups that spread in the land and existed for millennia.[6]