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.
History of the Middle East
Arabian culture took off during the early Abbasid age, despite the prevalent political issues. Muslims saved and spread Greek advances in medicine, algebra, geometry, astronomy, anatomy, and ethics that would later finds it way back to Western Europe. The works of Aristotle, Galen, Hippocrates, Ptolemy, and Euclid were saved and distributed throughout the empire (and eventually into Europe) in this manner. Muslim scholars also discovered the Hindu-Arabic numeral system in their conquests of south Asia. The use of this system in Muslim trade and political institutions allowed for the eventual popularization of it around the world; this number system would be critical to the Scientific revolution in Europe. Muslim intellectuals would become experts in chemistry, optics, and mapmaking during the Abbasid Caliphate. In the arts, Abbasid architecture expanded upon Umayyad architecture, with larger and more extravagant mosques. Persian literature grew based on ethical values. Astronomy was stressed in art. Much of this learning would find its way to the West. This was especially true during the crusades, as warriors would bring back Muslim treasures, weapons, and medicinal methods.