During the Abbasid Caliphate’s Golden Age, the Arabic script was reformed. The Abbasids moved their capital from Damascus, a Semitic (Aramaic) language center, to Baghdad in Persia. Arabic became a second language for most of its speakers in Baghdad, people with a completely different (Indo-European) language background. They began to study it carefully, as few languages had been studied at that time.
In nearby Basra, a linguist known as al-Farahidi began to update and reform Arabic writing. His goal was to standardize writing for poetry, and he also wrote a dictionary. The chief reform was to use a simpler vowel marking system. There had been experiments with using dots over and under the flowing consonants, sometimes with different color. Al-Farahidi worked out a simpler way, and he also added an extra consonant.
Al-Farahidi’s patches on the system made it possible to actually read Arabic without being a Bedouin. The enormous effort put into translation in Baghdad was only possible because they now had a workable writing system. Eventually, the Koran was rewritten with the new system. Persian, previously written with cuneiform, moved to the Arabic script. When the Turks began to invade and gradually got converted to Islam, their languages were first written in it, too. Eventually, all eminent scholars had to know the Arabic script.