 A few days after the fighting began, Muhammad ordered the razing of a large area behind the walls, so that the defenders would have more room to operate in.Muhammad had numerous sources of manpower in his allies and in the people of Baghdad.He could rely on many friendly military commanders to heed his call for assistance, and in the early months of the war several small regiments from Iraq, the Jazira, the Jibal, the Arab-Byzantine frontier and elsewhere arrived in Baghdad.