Original sentence: After fifty years it became the capital of the Don Cossacks, first as an independent entity in between Russia, Turkey and Poland, then a vassal of the Russian [[tzars], then as an administrative region, the Don Voisko Province, of the Russian Empire
Edited sentence: After fifty years it became the capital of the Don Cossacks, first as an independent entity in between Russia, Turkey and Poland, then a vassal of the Russian tzars, then as an administrative region, the Don Voisko Province, of the Russian Empire