Ardhan, also known as Albania, was a Caucasian satrapy which existed from 252 AD to 643 AD. In 252 AD, the Persian Sassanid Empire conquered Ardhan, and Ardhan retained its monarchy. Shah Yazdegerd II required all Christians in Ardhan to convert to Mazdakism, fearing that the Christians would ally with the Christianized Roman Empire. In 643 AD, the satrapy was conquered by the Arabs of the Rashidun Caliphate.