Where does “チェルカースィ” come from?

チェルカースィ (Japanese) comes from Ukrainian Черка́си, from Ukrainian -и.

Ancestry of “チェルカースィ”, step by step

StepLanguageWordMeaning
1UkrainianЧерка́си—
2Ukrainian-и—
Every word from Ukrainian -и →Every word from Ukrainian Черка́си →