According to the Muslim understanding, the Qur’an was revealed to the Prophet Muhammad over 23 years, from the age of 40 to his death at the age of 63. Over those 23 years, he received the revelation from God in a number of ways. Most commonly, it was spoken to him directly by the Angel Gabriel, but at other times it came during his dreams, and on a number of occasions, it even came to him directly from God, and he experienced this as the sound of a heavy bell, after which the words of the revelation were made clear to him.
Throughout those 23 years, the Prophet endeavoured to share the revelation with those around him as soon as it came. He did this verbally, as he couldn’t read or write, but he strongly encouraged others around him to write down the revelation, as well as memorise it. This was the basis of how Muslims believe the Qur’an became preserved, not purely through written or oral means, but with both strengthening the other. The companions around him constantly strove to memorise the verses, with many eventually memorising the entire book, and simultaneously wrote these verses on parchment, bone, wood, stone, basically whatever they had around them. Over time at least 65 companions functioned as scribes for the Prophet , who eventually established a school in Madinah dedicated to teaching 900 of his companions to read and write.
However, the dialect of the Quraishi tribe that the Prophet spoke in was not the only dialect of the Arabian peninsula, and as the religion was adopted by a growing number of tribes, they began to struggle with understanding the Qur’an. To overcome this, the Prophet was given permission to teach the Qur’an in 7 of the main dialects in the region, allowing the message to be understood more widely. These dialects didn’t affect the written records, as they were only different when the Qur’an was actually vocalised.
This was the state of the Qur’an at the death of the Prophet . Hundreds of companions who had memorised the complete Qur’an in 7 official dialects, all of which were considered valid ways of reciting the Qur’an, as well as an incredible amount of written records that were held by the Prophets companions throughout Madinah and beyond. The placing of each verse within each chapter had been established by the Prophet , but because each chapter functions as an independent unit, the companions had different ways of ordering the chapters themselves within the book as a whole.