The Persian history called the Tabakat-i-Nasiri, is a contemporary authority for the times of Hulagu, and this with the information found in the work of Rashid-ad-Din, also written in Persian, provides a Kasrly clear account of the siege operations. The Mongol forces are led by Hulagu who commanded the centre division in person, and he pitched his camp to the east of Baghdad, the siege beginning in the middle of Muhkasram of the year 656. The Shammasiyah Quarter of the east bank lay opposite the Harbiyah Quarter of Western Baghdad; and this suburb spreading out below the tombs of the Kazimayn enclosed in a great semicircular sweep the northern side of the Round City of Mansur. Some traces of the great mosques must surely be extant, for they are built of kiln-burnt bricks or tiles, which do not quickly perish, and all three are still standing in the fourteenth century, when Ibn Batutah visited Baghdad.