In one of his videos, Noam Chomsky, the famed linguist, mentions that if one were to look at Europe, in a lot of places local variations in language could be so prominent that sometimes even neighbouring villages would be mutually unintelligible. He says that modern socio-political phenomenon like formation of nation-states could lead to homogenizations that we see today. If this linguistic information in transplanted onto 7th century Arabia, would it be right to say that such local variations would have existed in Arabic also? If so, can we tell which dialect the Qur'an was written in, and in particular, what would this mean for the oral transmission and recitations of it? In the context of a nascent religion, would I be right in imagining a far-off Arab tribe reciting God's message in a dialect that they could not understand themselves? Finally, does the existence of Qur'an in a specific dialect mean something for large scale linguistic phenomenon - could the Qur'an be responsible for triggering some sort of homogenization in Arabic by the virtue of its authority?
The Mushaf of Uthman - the Quran used today - is written and read in the Qureyshi dialect of the Qureyshi Arab tribe of Mecca.
The Quraysh were a very well respected tribe historically and traditionally amongst the other Arab tribes, lived in Mecca, and engaged in long-distance seasonal trade with the Levant and southern Arabia. Their high regard amongst other Arab tribes was mainly due to their position as wardens of the Ka'aba and its numerous idols and as hosts of the annual religious festivals in Mecca in which Arab tribes from all corners of Arabia came to take part and engage in great trade and social activity and in religious pagan rites. Because of this, Qureyshi Arabic already had an elevated position of sorts amongst other Arabic dialects, although how pronounced this was is unclear.
Prophet Muhammad sw was himself a member of the Quraysh tribe, and many if the first companions - Sahaba - of the Prophet sw like Abu Bakr, Omar, Ali, and others were also Qureysh tribesmen. As such, the Quran was also revealed in Qureyshi Arabic for this reason as well.
However, the Prophet sw allowed non-Qureyshi Arab tribes to write and recite the Quran in their own dialects although the meaning could not be altered. This meant that the Quran of an Al-Azd tribe would be written in their dialect, and differences would only be in direct word equivalent replacements, insertions, and deletions and built-up phrasings in which the meaning would be exactly the same as the original Qureyshi Quran.
A good example of this would be the San'aa manuscript of the 6th century AD - the earliest Quranic script found. People have used the document as proof to show how the Quran is not unchanged, as the San'aa manuscript itself had minor word differences, replacing certian words with equivalent ones and minor deletions/insertions and rephrasings. Proponents of such a claim don't seem to grasp that the existence of such Quranic scripts and such variation in Quranic texts was explicitly allowed by the Prophet sw and in Shariah, so long as the meaning has not been altered. The San'aa manuscript, despite its differences and diffrentiation to the Qureyshi Quran, has been shown to not have produced any alteration to the meaning of the Qureyshi Uthmani Quran. As such, one is even allowed to recite the Quranic texts of the San'aa manuscripts in the Masjid al-Haraam (Mecca) when leading prayer, and although a large portion might not see any obvious differences at first, those who do notice will understand it to be a rare Quranic form and recitation. The Islamic Scholars (Ulema) will certainly be curious enough to ask, although one who is greatly familiar with the linguistics or speaks Yamani Arabic dialects might be able to pick up the word differences.
The Arabic of the dominant Uthamni Quran - that revealed to the Prophet - is now referred to as classical Arabic, and had become a lingua franca standard Arabic during the Rashidun caliphate, influencing other Arabic dialects and homogenizing them significantly. It also serves as a basis for standard Arabic, which is used and understood throughout the Arab world and used by non-mutually intelligible Arabic dialect speakers as a lingua franca of sorts.
/u/shlin28, would you have something to add to the answer of /u/asrafael, especially since you do not rule out the plausibility of an earlier Qur'an? How well has linguistic analysis served the skeptic faction of historians?