Complex sentence: The Semirechye Cossask Host supported the colonial policy of the Tsar in Kyrgyzstan and Kazakhstan, took part in conquering Central Asia and in World War I. During the Russian Civil War, the prosperous leadership of the Semirechye Cossask Host opposed the Soviets.
Split into simpler sentences: The Semirechye Cossask Host played a role in the expansionist colonial policy of the Tsar in Kyrgyzstan and Kazakhstan. Semirechye Cossacks took part in the conquest of Central Asia and in World War I. During the Russian Civil War, the prosperous leadership of the Semirechye Cossask Host opposed the Soviets.