Azarbaijan lay to the west of the Caspian Sea. 1ne region was so called because of the large number of its fire temples.
During the caliphate of Umar when the Muslims overpowered Persia, as column of the Muslim force under Hudhaifa b Alyaman invaded Azarbaijan. The Muslim force marched to Jurjan, where the local garrison surrendered after some resistance.
From Jurjan the Muslim force advanced to Ardbeei the capital of the province. The citizens did not choose to fight. They surrendered and agreed to pay the usual "Jizya".
Thereafter the Muslim force marched northward along the western coast of the Caspian Sea. In a confrontation at Bab, a port on the Caspian Sea, the Persians were defeated and the town was captured by the Muslims.
After some time on the transfer of Hudhaifa, the people of Azarbaijan revolted, and they met some initial success As a consequence, the Muslims had to abandon the advanced posts in Azarbaijan.