If you can read Russian, I suggest looking in the excellent Russian Wikipedia article about the document: https://ru.wikipedia.org/wiki/Письмо_запорожцев_турецк

If you can read Russian, I suggest looking in the excellent Russian Wikipedia article about the document: https://ru.wikipedia.org/wiki/Письмо_запорожцев_турецкому_султану https://ru.wikipedia.org/wiki/Письмо_запорожцев_турецкому_су... TL;DR the letter most likely is an 18th century Russian translation/modification of a typical 17th century Polish anti-Turkish pamphlet which was taken as genuine by 19th century Ukrainian nationalists.