The Arabic script grew from the cursive Aramaic writing of the Nabataeans, the trading people of Petra, whose late inscriptions shade by degrees into recognisably Arabic letterforms in the centuries just before Islam. At the Prophet Muhammad's lifetime it was still a bare consonantal skeleton, short of letters for all the sounds of Arabic and without the dots that now distinguish letters of identical shape. The needs of the Quran drove its completion. As the revelation was gathered into a fixed written text, scribes and grammarians of the first Islamic centuries added the i'jam, the pointing that separates otherwise identical letters, and the harakat, the small vowel signs, so that the sacred text could not be misread.
Tradition associates the earliest vowel notation with the grammarians of Basra, and the system reached its mature form in the hands of the early masters of Quranic orthography. The result is an abjad of twenty-eight letters, written right to left, whose full vocalisation is reserved in practice for the Quran itself, the one book in which no ambiguity of reading is tolerable. From Spain to Southeast Asia the script travelled with the faith, and was adapted to Persian, Ottoman Turkish, Urdu, Malay and many other languages.