Thanks for that link.  I should really have explained a bit: essentially they are a primitive variety of zither, in which the whole instrument is made of one piece of hollow wood, typically bamboo in the East, maize in Eastern Europe.  "Each string is a thin strip of bark cut loose from the...stem in such a way that its ends are not severed entirely; it is held away from the stem by bridges.  Such "idiochord" strings are often used singly, and their percussion character is prominent even to the point of their being played with sticks or beaters like a dulcimer..."  (Musical Instruments Through the Ages, ed. Anthony Baines, 1961.)

Malcolm