The Buwayhid dynasty, the Shiite rulers of Western Persia, capture Baghdad, adopt the title of Sultan and rule the caliphate from their capital in Shiraz. This marks the decline of the Abbasid dynasty as a political power.
Editors. "Persian Buwayhids capture Baghdad". The Literary Encyclopedia. First published 01 May 2009
[http://www.litencyc.com/php/stopics.php?rec=true&UID=7049, accessed 26 May 2013.]