When the Islamic Ummayads were in power, everything went well. They conquered Palestine, Mesopotamia, Persia, India, Afghanistan, Egypt, North Africa, Spain, Sicily, Cyprus, part of Turkey, and the islands off Spain--Minorca and Majorca. They also extended their conquests to the approaches to China when they conquered Turkestan and entered the Sind Valley. They went north from Spain into France, after taking Narbonne and other cities, and then went west and conquered Portugal.
They were intolerant in the beginning but changed in Spain. Christians and Jews occupied positions of honor. Their currency included the cross, as did many of their public buildings. For the most part, they were killed off by non-Arabs from Persia and Iraq, led by some Arabs called Abbasids who had their own form of Islam. One Umayyad--the nephew of the leading Umayyad killed in Egypt by assassins--Abdur al-Rahman, escaped to his mother's Berber family, in what is now Morocco, and went into Spain. There he continued the Umayyad tradition of acceptance of the people of the book. Using that, he created a powerful, tolerant, educated society that used mosques as centers of learning and finance ministers who were Jews and were entrusted with international business and foreign diplomacy. They kept their Muslims as good farmers and soldiers.