Ironically, borsch is actually a famous Ukrainian soup and has about 20 ingredients (sometimes more, it depends on a region, village and family). Why one would reduce to only 4 ingredients and continue calling it borsch is beyond me.
Regarding cabbage, it is indeed the only ingredient of a different soup, called "schi", which (perhaps unsurpisingly) is of Russian origin.
Regarding cabbage, it is indeed the only ingredient of a different soup, called "schi", which (perhaps unsurpisingly) is of Russian origin.