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.
Arabs
Another important and unifying characteristic of Arabs is a common language. Arabic is a Semitic language of the Afro-Asiatic Family. Evidence of its first use appears in accounts of wars in 853 BCE. It also became widely used in trade and commerce. Arabic also is a liturgical language of 1.7 billion Muslims.