The collection of folk music materials, collected by Emilis Melngailis between 1899 to 1943. The collection holds more than 10.000 folklore units, half of them - transcripts of melodies, and 46 photographs, which is the largest number of photographic images in a single collection in the inter-war period.

Emilis Melngailis is one of the most prominent folk music collectors in Latvia. He studied music in Dresden and St. Petersburg. In his collecting efforts he travelled Latvia and Lithuania, also writing down the melodies of other ethnic groups (like the Jews (he designates them 'Hebrew'), and the Livonians – the people that once gave the name to the territory that is now known as Latvia). Emilis Melngailis also took photos of his informants and their environment. The material collected by him were published in the three volumes of the book “Latviešu mūzikas folkloras materiāli” (The Materials of Latvian Musical Folklore): in 1951 Korsa (the western part of Latvia) with 1,326 melodies, in 1952 Maliena (the eastern part) with 1,676 and in 1953 Vidiena (the midlands) with 1,153 melodies, appendix and an endnote with an interesting motto: It is not possible to tell the depth without wading in.