There is much speculation about when the set was composed, but some of the most reliable sources point to it being composed somewhere between 1914 and 1918, in a period where Bartók felt very fascinated with folk music from Romania and his native Hungary.
Many of the small compositions he wrote when collecting folk music all around these countries was either lost or revamped into later works, and some would never see the light of publication.
After moving to the United States, Bartók lived in near-poverty, due to the lack of money his music could make him.
However, one of his main sources of income was to publish old manuscripts.
[1] The set consists of three short folk tunes.