I will agree. It seems as if most of the lands they seized were in conquest in the name of the one, true God. I find it hard to reconcile that Islam itself is supposedly a peaceful religion (like many imams will tell you) but yet the only way it seemed to advance was through war.
It is probably important to note that Islam was born of nomadic peoples that had barbaric practices compared to what was understood as civilized at the time. This could be why these sorts of things still happen today in Arab nations – it is so embedded in their heritage and culture to understand human rights in such a fundamentally different way than we do.
I’m not saying it’s right, but I am highlighting possible explanations.