I had a thought. In the medieval court of Yaroslav the Wise there was a semi-legendary bard by the name of Boyan. He is mentioned in the lay of Prince Igor (I can't remember if he features in the opera or not) and became a very popular folk figure. He would accompany himself on the gusli, a form of psaltery. A hundred years or go a form of button accordeon was invented in Russia and named the Bayan, in honour of Boyan. It became immensley popular for both dance tunes and for ACCOMPANIYING FOLK SONGS!!!!
Why? It could play not only the top line, but chords, bass and pretty much whatever your fingers wanted to do. Forget balalaikas, the bayan is seen by most people as the national instrument.