Complex sentence: The journal was formed in 1969 by the merger of two older publications: "Bijdragen en Mededeelingen van het Historisch Genootschap" (which began publication in 1877) and "Bijdragen voor de Geschiedenis der Nederlanden" (which began publication in 1946).
Split into simpler sentences: The journal was established in 1877 as the "Bijdragen en Mededeelingen van het Historisch Genootschap" (English: "Contributions and Communications of the Historical Society"). In 1969 it absorbed the "Bijdragen voor de Geschiedenis der Nederlanden" (English: "Contributions on the History of the Low Countries"; established in 1946).