The last of the seven-volume monograph on Mazovia was published from the remaining manuscripts of Kolberg’s collections. It contains supplementary material to the other two parts of Kolberg’s edition of Mazovia (i.e., parts 4-5), as well as extensive material from the field of beliefs and folk literature concerning the whole region, and not published by Kolberg. The supplementary part that completes the source material from Mazowsze Stare [Old Mazovia], according to Kolberg’s plan, is divided in volumes 4 and 5 into two sections: Mazury Kurpie [Masuria Kurpie] and Mazury Podlasie [Masuria Podlachia]. Within each of the volumes, however, there are included chapters devoted respectively to the description of the country, the people, customs, rites, universal songs (over 360), dances and melodies without texts (245). The part that constitutes the so-called non-supplementary inedited materials includes descriptions of beliefs (diseases, medicines and remedies, beliefs associated with nature, conceptions of the world, demonology, divination, superstitions), 78 folk tales, about 30 proverbs and riddles, 29 games (with 12 songs with melodies), a chapter devoted to the language (samples of speech, a list of peasant names, dialect glossary), and a list of towns from over a dozen districts of the region. The material comprised in the volume comes from Kolberg’s own research (particularly the documentation of musical folklore and over 40 folk tales), his co-workers (R. Korbasiński from Porządzie near Wyszków, L. and M. Czartkowski from Siemiatycze, P. Jaholkowski from Łomża, and others), and from literature (works of Z. Gloger, J. Grajnert, A. Osipowicz, K. Kozłowski, A. Połujański, K. W. Wójcicki, and others), and also from the press.