I want to say Стары Ольса (Stary Olsa) are my favorite non-metal folk band, but to be honest I have only heard two of their albums. That just might suffice. Stary Olsa formed in Belarus in 1999. Келіх кола (Loving Cup) is their first album, and they have released eight more since (of which I have only heard their first live album, Шлях (Šlach). It contains much of the same material.) So I can’t really speak for the band as a whole, but Loving Cup is easily one of the best albums in my entire musical collection. Their self-described style is “medieval”, though I don’t know if the Belarusian word they use, сярэднявечнай, carries precisely the same context (it is not a cognate). Their music lacks (to its advantage) a lot of the formalism I associate with western early music. (The average Drolls song will give you an idea of what I mean.) There’s something a lot more free-spirited about Stary Olsa’s sound, which lends it closer continuity with modern folk.
Part of that is an inevitable consequence of the most awesome instrument in the world: the bagpipe. (Did I say the whistle was my favorite just a few days ago? Ah well, close enough.) Stary Olsa do a wonderful job of going into thorough detail about the instruments and styles they employ on their official website. Unfortunately the English translations they provide are not very fluent. Stary Olsa employ three different variants of the Belarusian bagpipe, known as a duda. In the case of this song they also use some more contemporary instrumentation. I gather from what their site says that the flute is in fact a standard modern flute, or something close to it. They make no mention of the tambourine, but I have to wonder just how common an instrument that required metal could have been. The drum they use is likely an authentic medieval instrument, though I’m no good at guessing which. The hurdy gurdy has been known in Belarus since the late 16th or early 17th century, called there the колавая ліра, or “wheel lira”.
Танцы (Dances) is not my favorite Stary Olsa song though. There’ll be plenty more by them to come. In the meantime, you can check out a live recording of this song.