Common misconception.

The majority of the “Muslim” empire was not Muslim. It was under Muslim rule, but none of them were forced to be Muslim.

Islam was and is spread through reasoning and people just being convinced by it.

I don’t deny the battles, that’s just ignorant, but if you don’t know the motive behind these battles then I would suggest you properly study them before trying to claim something that doesn’t exist. They were mainly caused by self defence. The Persian empire and the Roman Empire didn’t like the new upcoming Islamic nation. Then the Byzantine empire and all the following and “coexisting” empires and nations.