Proto-Arabic language
Proto-Arabic is the name given to the hypothetical reconstructed ancestor of all the varieties of Arabic attested since the 9th century BC. There are two lines of evidence to reconstruct Proto-Arabic: Old Arabic in the Nabataean script is first attested in the Negev desert in the 1st century BC, but it becomes more frequent in the region after the decline of Safaitic and Hismaic. From the 4th century AD, Old Arabic inscriptions are attested from Northern Syria to the Hejaz, in a script that is intermediate between cursive Nabataean and the Kufic script of Islamic  times. The urheimat of Proto-Arabic can thus be regarded as the frontier between northwest Arabia and the southern Levant. Characteristics. There are several features shared by Classical Arabic, the varieties of Modern Arabic and the Safaitic and Hismaic inscriptions that are unattested in any other Semitic language variety, including the Dadanitic and Taymanitic languages of the northern Hejaz. They are evidence of common descent from a hypothetical ancestor, Proto-Arabic. The following features can be reconstructed with confidence for Proto-Arabic: