Where does “vierustoveri” come from?

vierustoveri (Finnish) comes from Finnish toveri, from Russian това́рищ, from Old East Slavic товарищь, from Proto-Slavic tovarišь, from Proto-Slavic tovarъ, from Proto-Turkic *tabar — livestock, cattle.

Ancestry of “vierustoveri”, step by step

vierustoveri traces back through two separate lines of ancestry.

via Finnish toveri

Step	Language	Word	Meaning
1	Finnish	toveri	comrade; companion, buddy
2	Russian	това́рищ	comrade
3	Old East Slavic	товарищь	—
4	Proto-Slavic	tovarišь	—
5	Proto-Slavic	tovarъ	loading
6	Proto-Turkic	*tabar	livestock, cattle

via Finnish vierus

Step	Language	Word	Meaning
1	Finnish	vierus	—
2	Finnish	vieri	side; Third-person singular indicative past form...
3	Proto-Finnic	veeri	side, flank; edge
4	Proto-Finno-Permic	wäre	—

Every word from Proto-Turkic *tabar →Every word from Proto-Slavic tovarъ →Every word from Proto-Slavic tovarišь →