Опольское княжество
The formal contract of mutual inheritance was performed in 1511 between the childless Duke Valentin and Jan II. The contract, who counted with the approval of King Władysław II Jagiellon, came into force after the death of Valentin in 1521: Jan II inherited the Duchy of Racibórz, who was combined with the Duchy of Opole. The newly Duchy of Opole-Racibórz covered an area from the Ścinawa and Nysa Kłodzka Rivers in the West, the Sudetes and the Vistula River in the south, and the borders with Poland in the east and north. This represented a territory the size of 12,000 kilometers.