After Russia conquered the entire Finnish territories in yet another Russo-Swedish war in 1808–09, it was decided to join the Karelian Isthmus and Ladoga Karelia to the newly formed Grand Duchy of Finland in 1812, which brought all western Karelians into the same state with Finns, while eastern Karelians remained under independent Russian administration. Although Karelians ended up in the same country the religious difference between eastern and western Karelians remained a dividing factor, which somewhat affected the linguistics but even until the beginning of the 20th century both groups could understand each other. Yet eastern Karelians managed to preserve traditions and folklore better than western Karelians.