Before the days of Muhammad, “Christian” conquerors had occupied Jerusalem (within the Byzantine Empire). Bringing one’s religion into battle demonstrated that both their armies and their religion were superior to those of their victims when they won. So, they usually built their holy places on top of their victims’ holy places, which they did on the Temple Mount, to absorb the strength of their conquered adversaries and to convert them to their religion. Even under the threat of the sword, the Jews refused to convert and allow their lineage to be absorbed, which would in effect, transfer God’s Covenant.
Muhammad died in 632 c.e. Jerusalem was subsequently captured from the Romans by caliph Omar, six years after Muhammad’s death as explained in details at : http://xrl.us/bjheo