Ah you must be one of those that still holds on to āAl jalladā the amateur who studied under well known orientalists who try their best to change the history of Arabs based on āgraffitiā found on stones in Iraq, Syria and Jordan not knowing that Arabs had 1000s of classical scholars throughout the last millennium and half some of whom literally witnessed the migration of these Arabs themselves and were closer in time to when the Arabs were getting dispersed. Not to forget that this is the age of archeogenetics. It goes completely against scientific logic for Arabs to have arrived from the north with all the genetic material we have available. Even the Arabic inscriptions your on about are text written by tribes with historical origins further south in Yemen. Case in point is the 2nd oldest Arabic inscription the Namara inscription, an epitaph of the Lakhmid king Imru' al-Qays bar 'Amro, dating to 328 CE, found at Namaraa, Syria. Itās well known that Lakhmids migrated from Yemen in the 2nd century AD to settle in the Fertile Crescent. Arabic you hear today used to be just one out of many closely related dialects spoken before the advent of Islam. Even today the Arabs with the closest speech to the classical 7th century āHejaziā dialect are spoken by tribes with southern origin near the borders of Yemen. Ahmed Abdul Ghafur Attar, a Saudi poet and linguist said in an article that the language of the Hejaz especially that which is spoken in Belad Ghamdi and Zahran, is close to the Classical Language. Faisal Ghori, a famous scholar of Arabic literature, in his book Qabayil Al- Hejaz (Hejazi tribes) wrote: "We can say is that there are some tribes in Arabia whose language today much closer to the classical Arabic language. The tribes of Belad Ghamid and Zahran are a good example of this." Both Zahran and Ghamid are of Qathanite southern stock near the borders with Yemen. If they adopted Arabic they would not have spoken the purest form of it. They would have had substrates.