David Nicolle 
Armies of the Muslim Conquest [PDF ebook] 

The dramatic eruption of the Arab peoples from Arabia after their adoption of the Muslim faith in the 7th century remains one of the most extraordinary events in world history. By the end of that century they ruled a state that stretched from the Atlantic to India, from southern Arabia to Central Asia, covering an area far greater than that of the Roman Empire. Therefore warfare, at least among the nomadic bedouin, was a normal aspect of life. Complemented by numerous illustrations, including eight full page colour plates by Angus Mc Bride, this detailed text by David Nicolle tells the real story of the armies of the Muslim conquest.