The Koran is probably THE greatest piece of plagiarism ever written...the old Testament is what it attempts to copy. Mohammed appears to have been influenced by Jewish and Christian monotheism and in 610, as he was asleep or in a trance,the "truth" came to him. Since he could neither read nor write, he dictated his version of things...the Koran.
One of many good websites:
http://members.ozemail.com.au/~dbates/koran.htm
Mo was influenced by Arianism, an early Christian heresy that was driven out of Roman lands by the church. This was tolerated by the Ethiopians who ruled the Horn of Africa and Yemen until the 6th century. As an aside, did you know that hte Ethiopian Empire tried to conquer and destroy Makkah in Mo's father's generation's time?