Semitic languages
The similarity of the Hebrew, Arabic and Aramaic languages was accepted by Jewish and Islamic scholars since medieval times. The languages were familiar to Western European scholars due to historical contact with neighbouring Near Eastern countries and through Biblical studies, and a comparative analysis of Hebrew, Arabic, and Aramaic was published in Latin in 1538 by Guillaume Postel. Almost two centuries later, Hiob Ludolf described the similarities between these three languages and the Ethiopian Semitic languages. However, neither scholar named this grouping as "Semitic".
Levantine Arabic
Ancient Arabia was home to a continuum of Central Semitic languages in antiquity which stretched from the southern Levant to Yemen. The isoglosses associated with Arabic are clustered at the northern end of this continuum, in the northern Hijaz and the southern Levant. This may be in part due to a lack of documentation, but it is clear that Central Arabia was home to languages quite distinct from Arabic. Thus, Arabic can be said to have emerged in the second millennium BC and spread into the peninsula, replacing its sister languages on the Central Semitic continuum.