The Ruin is a historical term introduced by the Cossack chronicle writer Samiilo Velychko (1670–1728) for the political situation in Ukrainian history during the second half of the 17th century.

Bohdan Zynoviy Mykhailovych Khmelnytsky was a Ruthenian nobleman and military commander of Ukrainian Cossacks as Hetman of the Zaporozhian Host, which was then under the suzerainty of the Polish–Lithuanian Commonwealth. He led an uprising against the Commonwealth and its magnates (1648–1654) that resulted in the creation of an independent Cossack state in Ukraine. In 1654, he concluded the Treaty of Pereiaslav with the Russian Tsar and allied the Cossack Hetmanate with Tsardom of Russia, thus placing central Ukraine under Russian protection. During the uprising the Cossacks led a massacre of thousands of Poles and Jews during 1648–1649 as one of the most traumatic events in the history of the Jews in Ukraine and Ukrainian nationalism.