“Quickly, the Muslims united most of Arabia under their rule.” p.453 My World History (Early Ages)
The word united is a whitewash of the facts. United sounds so peaceful and good to the mind of a child.

But how did Muhammad unite Arabia?
From Muhammad’s headquarters in Medina, Islamic writings account the following.

“The major battles waged by Muhammad from Medina were directed largely against the Quraish Tribe. According to the Sira (659-660), the Muslims under Muhammad engaged in some eight-four battles and raids between AD 622 and 632. Muhammad was present for twenty-seven of these and personally fought in nine. Four engagements, however, stand out; the battles of Badr, Uhud, The Trench, and Mecca. Details of these battles illuminate the essential nature of violence in Islam and provide orthodox Muslims with a blueprint for their own conduct.”
by Gregory M. Davis, Religion of Peace