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.
Old Arabic
Old Arabic is the earliest attested stage of the Arabic language, beginning with the first attestation of personal names in the 9th century BC, and culminating in the codification of Classical Arabic beginning in the 7th century AD. Originally the primary language of the Safaitic and Hismaic inscriptions, it came to be expressed primarily in a modified Nabataean script after the demise of the Nabataean Kingdom. In addition, inscriptions in Old Arabic are attested in the Dadanitic script and the Greek alphabet, the latter of which have proved indispensable in the reconstruction of the language's phonology.