The Arabic alphabet is thought to be traced back to a Nabataean variation of the Aramaic alphabet, known as Nabataean Aramaic. This script itself descends from the Phoenician alphabet, an ancestral alphabet that additionally gave rise to the Armenian, Cyrillic, Devanagari, Greek, Hebrew and Latin alphabets. Nabataean Aramaic evolved into Nabataean Arabic, so-called because it represents a transitional phase between the known recognizably Aramaic and Arabic scripts. Nabataean Arabic was succeeded by Paleo-Arabic, termed as such because it dates to the pre-Islamic period in the fifth and sixth centuries CE, but is also recognizable in light of the Arabic script as expressed during the Islamic era. Finally, the standardization of the Arabic alphabet during the Islamic era led to the emergence of classical Arabic. The phase of the Arabic alphabet today is known as Modern Standard Arabic, although classical Arabic survives as a "high" variety as part of a diglossia.
There were different theories about the origin of the Arabic alphabet as attested in Arabic writings, The Musnad theory is that it can be traced back to Ancient North Arabian scripts which are derived from ancient South Arabian script (Arabic: خَطّ الْمُسْنَد ḵaṭṭ al-musnad), this hypothesis have been discussed by the Arabic scholars Ibn Jinni and Ibn Khaldun. Ahmed Sharaf Al-Din has argued that the relationship between the Arabic alphabet and the Nabataeans is only due to the influence of the latter after its emergence (from Ancient South Arabian script). Arabic has a one-to-one correspondence with ancient South Arabian script except for the letter 𐩯 (reconstructed Proto-Semitic s³).
