The interwar period was the time of rapid development of Latvian humanities, especially in the field of folklore. Latvian researchers, thanks to their international contacts, transposed the newest methods of folklore research to Latvia, especially the geographical-historical method. In the years of 1930-1934 a Polish professor Julian Krzyżanowski, a prominent Polish philologist and later a folklore specialist, was working at Latvian University. Thanks to the contacts with Latvian folklorists, he got acquainted with the newest research methods in the field of folklore, especially with the Aarne–Thompson classification systems. Cooperation with Latvian folklorist Pēteris Šmits resulted to be exceptionally inspiring. Šmits's monumental work: Latviešu pasakas un teikas (Latvian fairy tales and legends) was an important inspiration for the classification of Polish folktales.