Numerical digit
From India, the thriving trade between Islamic sultans and Africa carried the concept to Cairo. Arabic mathematicians extended the system to include decimal fractions, and Muḥammad ibn Mūsā al-Ḵwārizmī wrote an important work about it in the 9th  century. The modern Arabic numerals were introduced to Europe with the translation of this work in the 12th century in Spain and Leonardo of Pisa's "Liber Abaci" of 1201. In Europe, the complete Indian system with the zero was derived from the Arabs in the 12th century.
Arabic
Beginning in the 1st century CE, fragments of Northern Old Arabic are attested in the Nabataean script across northern Arabia. By the 4th century CE, the Nabataean Aramaic writing system had come to express varieties of Arabic other than that of the Nabataeans.