Baghdad.. decay after the capital to Samarra, linking the Tigris covers of three bridges and the use of boats in the Tigris as intermediaries for the transfer between Rusafa and Karkh

After that the transfer of Caliph Billah capital Baghdad to Samarra known period degeneration, but soon returned to be the capital of the new.

During the reign of Caliph adopted focused cultural expansion on the east side, in Rusafa, which shrouded the Caliph Almstzar huge wall, has been linked to the covers of the Tigris three main bridges, and is used for boats in the Tigris as intermediaries for the transfer between Rusafa and Karkh, thereby Baghdad became their facilities and facilities with the largest agglomeration as the capital of the Islamic world.