Zaporozhian Sich

The Zaporozhian Sich (Ukrainian: Запорозька Січ, Zaporoz'ka Sich; Polish: Sicz Zaporoska; Russian: Запорожская Сечь, also Ukrainian: Вольностi Вiйська Запорозького Низового, Volnosti Viyska Zaporozkoho Nyzovoho; Free lands of the Zaporizhian Host the Lower)[1] was a semi-autonomous polity and proto-state[2] of Cossacks in the 16th to 18th centuries, centred in the region around today's Kakhovka Reservoir and spanning the lower Dnieper river in Ukraine. In different periods the area came under the sovereignty of the Polish–Lithuanian Commonwealth, the Ottoman Empire, the Tsardom of Russia, and the Russian Empire.

Historical map of the Ukrainian Cossack Hetmanate (dark green) and of the territory of the Zaporozhian Cossacks (purple) under the rule of the Russian Empire (1751)

In 1775, shortly after Russia annexed the territories ceded to it by the Ottoman Empire under the Treaty of Küçük Kaynarca (1774), Catherine the Great disbanded the Sich. She incorporated its territory into the Russian province of Novorossiya.

The term Zaporozhian Sich can also refer metonymically and informally to the whole military-administrative organisation of the Zaporozhian Cossack Host.