Where does “Чьрниговъ” come from?

Чьрниговъ (Old East Slavic) comes from Old East Slavic чьрнъ, from Proto-Slavic čьrnъ, from Proto-Balto-Slavic kiršnas, from Proto-Indo-European kr̥snós, from Proto-Indo-European kers- — black, dirty; run; to run.

Ancestry of “Чьрниговъ”, step by step

Чьрниговъ traces back through two separate lines of ancestry.

via Old East Slavic чьрнъ

StepLanguageWordMeaning
1Old East Slavicчьрнъblack
2Proto-Slavicčьrnъblack
3Proto-Balto-Slavickiršnasblack
4Proto-Indo-Europeankr̥snósblack; dark, dusky
5Proto-Indo-Europeankers-black, dirty; run; to run

via Old East Slavic Чьрнигъ

StepLanguageWordMeaning
1Old East SlavicЧьрнигъ
Every word from Proto-Indo-European kers-Every word from Proto-Indo-European kr̥snósEvery word from Proto-Balto-Slavic kiršnas