 Complete the following phrase:  After Muhammad died in 632, his successors the Caliphs continued to lead the Muslim community based on his teachings and guidelines of the Quran. The majority of Muslims consider the first four successors to be rightly guided or Rashidun. The conquests of the Rashidun Caliphate helped to spread Islam beyond the Arabian Peninsula, stretching from northwest India, across Central Asia, the Near East, North Africa, southern Italy, and the Iberian Peninsula, to the Pyrenees. The Arab Muslims were unable to conquer the entire Christian Byzantine Empire in Asia Minor during the ArabByzantine wars, however. The succeeding Umayyad Caliphate attempted two failed sieges of Constantinople in 