The Avar Khanate was a long-lived Muslim state in Dagestan which existed from the early 13th century to 1864, with Khunzakh serving as its capital. The Avars formed their own state during the power vacuum created by the Mongol invasions of the North Caucasus, as the Orthodox Christian states were weakened by war. Under Turkish influence, during the 17th century the majority of Avar tribes adopted Islam, and the consolidation of Islam among the Avars led to a series of religious wars against the Georgian states during the 18th century. In 1741, the Avars defeated Nader Shah's invasion of Dagestan, and they expanded from mountainous Dagestan into the rest of Dagestan and Chechnya. From 1775 to 1801, the Avars reached the zenith of their power in the Caucasus. In 1803, the khanate voluntarily submitted to Russian authority, but the Russian administration (marked by heavy taxation, the exproproation of estates, and the construction of fortresses) angered the Avars and led to the Caucasus War. In 1864, after the war was ended, the Russian Empire abolished the Avar Khanate and replaced it with an "Avar District".