I was engaged in a relatively friendly chat with a friend of mine and the subject of Islam came up.
I seem to recall (from my religion class at college) that Mohammad actually asserted control (as in ‘rule’) over a section of the middle east. My memories fuzzy, hence my question in GQ;
Did Mohammad use Islamic followers to take over certain countries/cities while he was alive? I’m fairly certain that Islam was later spred by muslims (ie, taking over other countries), but I was wondering if Mohammad actually did this himself.
IANA expert on Arabic history, but I definitely know that under his leadership, Islamic troups conquered his birthplace, the city of Mecca.
When Mohammed was born, Arabia had no government of any kind. Clans and tribes were everything. Independent cities such as Mecca and Medina were not really city-states; public order was merely an uneasy peace between clans.
By the time of his death, Mohammed had established a theocratic state, a de facto monarchy, that united what are now Saudi Arabia, Yemen, Oman, and the United Arab Emirates. It was an ethnically homogeneous state – practically all its people were Arabs, apart from a Jewish minority.
It was the Prophet’s successors who expanded the Islamic empire into non-Arab countries – North Africa, Egypt, Mesopotamia (Iraq), and Persia (Iran). This stimulated Islam to evolve from an ethnic religion of the Arabs into a universalist religion.
For more details check out “Islam: A Short History,” by Karen Armstrong (Modern Library Chronicles series, 2000).
Cool, thanks for the info! 
By the way, you an also find a good (and fun-to-read!) account of the rise of Islam in “The Cartoon History of the Universe III,” by Larry Gonick (2002, W.W. Norton & Co.).