Muslim conquest of the Levant
In the 7th century the disastrous Byzantine–Sasanian War of 602–628 and the campaigns of Khosrow II and Heraclius facilitated the emergence of Islam in the Arabian Peninsula during the lifetime of Muhammad. Subsequent Muslim conquest of the Levant and Persia overthrew the Sasanian Empire and permanently wrested two thirds of the Eastern Roman Empire's territory from Roman control, forming the Rashidun Caliphate.