Spain, originally inhabited by Celts, Iberians, and Basques, became a part of the Roman Empire in 206 B.C., when it was conquered by Scipio Africanis. In A.D. 412, the barbarian Visigothic leader Ataulf crossed the Pyrenees and ruled Spain, first in the name of the Roman emperor and then independently. In 711, the Muslims under Tariq entered Spain from Africa and within a few years completed the subjugation of the country. In 732, the Franks, led by Charles Martel, defeated the Muslims near Poitier's, thus preventing the further expansion of Islam in southern Europe.
Spain occupies 85% of the Iberian Peninsula, which it shares with Portugal, in southwest Europe. Africa is less than 10 mi (16 km) south at the Strait of Gibraltar. Aragon and Castile were the most important Spanish states from the 12th to the 15th century, consolidated by the marriage of Ferdinand II and Isabella I in 1469. In 1478, they established the Inquisition, to root out heresy and uncover Jews and Muslims who had not sincerely converted to Christianity.