Al-Andalus was a multiethnic and plural society. Arabs and Berbers joined the Hispanic population, many of whom converted to Islam. The arrival of slaves from many different places added to the diversity. The Christian and Jewish communities were respected. Arabic spread, though neo-Latin languages survived. The Koran was the basis of Sharia, the Islamic code of law. The state, in the person of the caliph, maintained the unity of the Muslim community (umma). Religious groups regulated civil life through the law and schools and by determining what was politically legitimate.