query: When did the Ukraine join the Soviet Union?
passage: Ukrainian Soviet Socialist Republic
The Ukrainian Soviet Socialist Republic (Ukrainian SSR or UkrSSR or UkSSR; Ukrainian: Украї́нська Радя́нська Соціалісти́чна Респу́бліка, Украї́нська РСР, УРСР ; Russian: Украи́нская Сове́тская Социалисти́ческая Респу́блика, Украи́нская ССР , УССР ; see "Name" section below), also known as the Soviet Ukraine, was one of the constituent republics of the Soviet Union from the Union's inception in 1922 to its breakup in 1991.[6] The republic was governed by the Communist Party of Ukraine as a unitary one-party socialist soviet republic.
passage: Modern history of Ukraine
Ukraine first declared its independence with the invasion of Bolsheviks in the late of 1917. Following the conclusion of the World War I and with the peace of Riga, Ukraine was partitioned once again between Poland and the Bolshevik Russia, which on its occupied territory created own puppet state of its pocket communist party, the Ukrainian Soviet Socialist Republic.