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 in Europe
Arabs in Europe have a history beginning with the Arab Empire, which conquered the Iberian Peninsula, including what is now Spain and Portugal, in 711 AD. Other Arabs occupied the Italian island of Sicily from 831 to 1072. Arabs were later expelled from those domains after the Reconquista and the Catholic Church's Inquisition of non-believers. There were also brief periods of independent Arab-Islamic colonization and occupation, in modern-day France, Switzerland, and Italy, using Fraxinet in the Gulf of St. Tropez as a base for raids and colonisation.