After the death of Prophet
Muhammad the rapidly expanding Islamic nation was led by a series of men known
as the four rightly guided Caliphs. They were men that had learnt their Islam directly
from the Prophet himself and governed strictly according to the Quran and authentic
traditions of Prophet Muhammad. By 644CE both the Persian and Byzantium empires
had fallen to the Muslim armies. Slowly over the next decades the people of
the conquered empires adapted both the language and religion of the conquerors.