Zynoviy Bohdan Mykhailovych Khmelnytsky of the Abdank coat of arms (1595 – 6 August 1657) was a Ruthenian nobleman and military commander of Zaporozhian Cossacks as Hetman of the Zaporozhian Host, which was then under the suzerainty of the Polish–Lithuanian Commonwealth. He led the Cossacks to victory in a successful uprising against the Commonwealth and its magnates (1648–1654) that resulted in the creation of an independent Cossack state in Ukraine.
In 1648–1649, the Cossacks under Khmelnytskyi's leadership massacred tens of thousands of Poles and Jews, with more handed over as yasir (slaves) to his Crimean Tatar allies, one of the most traumatic events in Polish and Jewish history. Under his rule of the newly-established Cossack state, the massacres continued until at least 1652. In 1654, Khmelnytsky concluded the Treaty of Pereiaslav with the Russian Tsar and allied the Cossack Hetmanate with Tsardom of Russia, thus placing Ukraine under Russian protection.
