Also they had recently been struck by plague. Plague, man, I'm telling you, it's like the red tortoise shell of history. But in those early days they did pry away some valuable territory like Egypt and the Holy Land and then eventually they got into Spain, where various Muslim dynasties would entrench themselves until being expelled in 1492. But as good as they were at making war, it's still tempting to chalk up the Arab success to, you know, the will of God. And certainly a lot of the people they conquered felt that way. Empires in this part of the world didn't just pit people against each other, they also pitted their gods against each other. So while the Islamic empire didn't require its subjects to convert to Islam, their stunning successes certainly convinced a lot of people that this monotheism thing was legit.