This work, based on folk songs collected by the composer early in the twentieth century, was first published in the year 1918. The first publication contained the twenty pieces without requiring octave intervals from the player. A second printing was produced in 1936, containing certain corrections by the composer including a revised title page, as well as the appendix where some of the pieces or portions thereof appear in an expanded format, with octaves, requiring considerable skill.
This revised edition was prepared taking into consideration all the existing manuscript sources. In addition, the sources themselves have been examined and certain inconsistencies attributable to oversight have been corrected. (P. Bartók)