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.
Rebec
Popular from the 13th to 16th centuries, the introduction of the rebec into Western Europe coincided with the Arabic conquest of the Iberian Peninsula. There is however evidence of the existence of bowed instruments in the 9th century in Eastern Europe. The Persian geographer of the 9th century Ibn Khurradadhbih cited the bowed Byzantine lira (or "lūrā") as typical bowed instrument of the Byzantines and equivalent to the Arab "rebab".