The Kingdom of Georgia was unified in the Middle Ages under the royal house of Bagration which liberated the area from the Arabs who had been attacking the outer edges of the Byzantine Empire. Georgia expanded considerably until the Seljuk Turks invaded and eventually conquered most of the country. King David IV led the fight back against the Turks, eventually pushing the Turks out and expanding the kingdom once again. In 1121 the Turks declared a jihad against Georgia and sent a massive army but the Georgians defeated it. During the reign of Queen Tamar Georgia reached its Golden Age. This period held until the region was again laid low by the Mongol invasions. Periods of aggression by the Persians and Ottoman Turks followed. Georgia was incorporated into the Russian empire during the reign of Tsar Paul I. Georgia remained under Russian and then Soviet rule until the fall of communism and the breakup of the USSR.