Where does “czystka” come from?
czystka (Polish) comes from Russian чи́стка, from Russian чи́стить, from Proto-Slavic čistiti, from Proto-Slavic čistъ, from Proto-Balto-Slavic skīstas, from Proto-Indo-European skidtos, from Proto-Indo-European (s)keyd-.
czystka (Polish): purge, combing-out
Ancestry of “czystka”, step by step