Where does “Rosjanin” come from?

Rosjanin (Polish) comes from Polish Rosja, from Russian Росси́я, from Greek Ῥωσία, from Old East Slavic Русь, from Finnish ruotsi, from Proto-Finnic *roocci, from Old Swedish roþs-, from Old Norse róðr — to row; to separate; loose, sparse, rare.

Ancestry of “Rosjanin”, step by step

StepLanguageWordMeaning
1PolishRosja
2RussianРосси́яRussia
3GreekῬωσία
4Old East SlavicРусьRus; Ruthenia
5FinnishruotsiSwedish
6Proto-Finnic*roocciSwede originally anyone from Roslagen
7Old Swedishroþs-related to rowing
8Old Norseróðrrowing
9Proto-Germanicrōþrąoar; rudder
10Proto-Indo-Europeanh₁reh₁-to row; to separate; loose, sparse, rare
Every word from Proto-Indo-European h₁reh₁-Every word from Old Swedish roþs-Every word from Proto-Finnic *roocci