Between 632 and 720, the Muslim Arabs created an empire that extended from the Iberian Peninsula to the Indus River in modern Pakistan. The success of the conquests derived from a combination of high motivation on the part of the Arabs and the weakness of the Byzantines and Sasanians at the end of their mammoth, thirty-year war with each other. The new Umayyad Empireproved to be highly creative in adapting elements of Byzantine and Sasanian administrative practice, which allowed itto build a durable bureaucracy. On the other hand, its reputation for corruption and its bigotry toward non-Arabs led to a revolutionary opposition movement.