The Zaporozhian Cossacks, Zaporozhian Cossack Army, Zaporozhian Host, or simply Zaporozhians were Cossacks who lived beyond the Dnieper Rapids. Along with Registered Cossacks and Sloboda Cossacks, Zaporozhian Cossacks played an important role in the history of Ukraine and the ethnogenesis of Ukrainians.

The Polish–Lithuanian Commonwealth, formally known as the Kingdom of Poland and the Grand Duchy of Lithuania, or simply Poland–Lithuania, was a bi-confederal state, sometimes called a federation, of Poland and Lithuania ruled by a common monarch in real union, who was both King of Poland and Grand Duke of Lithuania. It was one of the largest and most populous countries of 16th- to 17th-century Europe. At its largest territorial extent, in the early 17th century, the Commonwealth covered almost 1,000,000 km2 (400,000 sq mi) and as of 1618 sustained a multi-ethnic population of almost 12 million. Polish and Latin were the two co-official languages, and Roman Catholicism served as the state religion.