The period of the Buyid supremacy lasted for rather more than a century, and was characterized by the erection of many fine buildings in the capital of the Caliphate. The Buyid princes built their palaces in East Baghdad, on the ground formerly occupied by the Shammasiyah and part of the MukKasrim Quarter; and these palaces, princes took over and enlarged, are known by the general name of the Dar-as-Saltanah. In Western Baghdad Karkh is still to be the most populous and preserved quarter, and here the merchants lived at the Yasiriyah suburb had their houses of business. Towards the close of the reign of the Caliph Nasir, Yakut wrote his great Geographical Dictionary, which forms perhaps the greatest storehouse of geographical facts compiled by any one man during the Middle Ages. In the dearth of authorities for the last centuries of the history of Baghdad, the great Biographical Dictionary compiled by Ibn Khallikan is a very useful work of reference.