If The Caliphate had split apart early on.
Sometime during the reign of Caliph Uthman ibn Affan (644-656)
The death of Hudhayfah ibn al-Yaman came suddenly, and not without great despair. He was the hero of Nahavand, where he defeated a Persian force five times his size in 641, and he was capable ruling official stationed in Iraq as well. There he became increasingly concerned with the rate at which the holy word of Muhammad, peace be upon him, was being corrupted, not only in content but in the words themselves.
In little over thirty years, the numerous tribes of Bedouin Arabs had rallied around the creed of Islam, creating a holy Caliphate from Libya to Pakistan and from Armenia to Yemen. The holy dialect written in the Koran was beginning to permeate the areas of various northern languages and had started to be recognized as the prestige language by the newly-converted populace. Aramaic dialects however remained to be the standard language of the majority of Mesopotamian and Syrian peoples, and Greek in particular stood as an "educated" language in the cities of the Levant.
Hudhayfah was displeased with the way the Koran was being treated around him. The holy prose and meter was being corrupted and replaced by local Arabic dialects, Arabo-Aramaic and even completely into Aramaic. As he was about to set fourth to Mecca to alert his lord Caliph Uthman ibn Affan of the careless debauchery and what heinous consequences many false messages may lead to, he was poisoned with a witch's drink and was dead within minutes, the assailant being a disgruntled Monophysite convert in his retinue
*.
By the time a sufficient amount of emissaries had convinced Uthman a standardization of the production of the Koran was necessary, it was too late. Monophysite Christianity had meshed with Islam to a point that versions of an Aramaic Koran claimed Muhammad was the son of god, which was considered sacrilegious by the Mecca-based Caliphate. With the help of uprising Persians, the Aramaic school of Islam formed, and a Caliph to rule over the church and its followers was established.
In Egypt, the shattering of the world of Islam meant that the Monophysites retained control, with Islam becoming a Minority religion. Coptic will survive for much longer, as there was less Arabic influence to change it and eventually overtake it.
The Tauregs and other nomads of Libya seem to be aligned with the Meccan Caliphate, but overall their distance, decentralization and lack of communication makes it so that they remain a relatively weak entity.
In Persia, Zoroastrianism remains strong, though with much influence from Islam (For example, Abraham, Moses, Jesus and Muhammad are all seen as prophets such as Zoroaster). The schools of Islam become significantly entrenched however, particularly in the mountainous region between Iran and Iraq.
By Uthman's death in 656, the political and religious (and to a lesser extent linguistic) status of the Middle East leave the region tense and set for a clash of empires.
*: The PoD. IOTL, Hudhayfah ibn al-Yaman traveled to Mecca were he advised Uthman to start a purge of all modified Korans and institute and standardized way to write the Koran. Without him, Uthman may not have been able to work fast enough to counter what was happening in Syria at the time, and that is where this TL starts.
