The music collection once belonging to the Collegium Braunsbergense Societatis Jesu, and now kept at the Uppsala University Library (Uppsala Universitetsbiblioteket), comes from the first period of the Braniewo collegium’s history, which ended in 1626 when the school’s seat was pillaged by the Swedish army, and its library stock was taken away. The sources which the invaders carried away to Sweden are the only material document of the collegium’s musical past. The musical collection of the Collegium Braunsbergense consisted of about 50 liturgical books with plainchant notation, prints and manuscripts comprising sacred polyphony, and a few individual theoretical treatises.