At the time of the advent of Islam, there were two very great empires in the world —the Christian Roman Empire and the Zoroastrian Persian Empire. There were constant clashes between these two. In the year 603 A.D., Iran (Persia) attacked the Roman Empire, taking advantage of certain weaknesses in the latter. The Romans suffered defeat after defeat, so much so that by the year 616 A.D., a large part of the Roman Empire, including Jerusalem, had been captured by the Iranians. The Prophet received the prophethood in the year 610 A.D.
