Along with other regions in the Middle East,^[1]http://www.timemaps.com/history/middle-east-500ad Mesopotamia passed from the Parthian empire to the Sassanid empire in AD 222. This Persian dynasty has created a centralized empire, and the small kingdoms which the Parthians tolerated have now come firmly under Sassanid control.

As in the Roman empire^[2]http://www.timemaps.com/europe-500ad to its west, new religions have spread in the region. Whilst the Persian ruling class is loyal to Zoroastrianism, Christianity is widespread amongst the population at large, and many of the cities house flourishing Jewish colonies. A new religion also makes its appearance in Sassanid Mesopotamia, that of Manichaeism.

Under the Sasanian dynasty of Persia, Iraq has experienced one of its golden ages. The ancient irrigation system has been brought up to a pitch never before seen; new land has been brought under cultivation; cities have flourished, and the population has expanded. Iraq is the breadbasket of the Persian empire. Economically, the region probably attains its highest levels prior to the twentieth century.