Complex sentence: Papen was proud that his family had since the 13th century been granted the hereditary right to mine salt at Werl, and he always believed in the superiority of the aristocracy over commoners.
Split into simpler sentences: Papen was proud of his family's having been granted hereditary rights since the 13th century to mine salt at Werl. Papen always believed in the superiority of the aristocracy over commoners.