Sion

The Prince-Bishopric of Sion was an imperial church state in the upper Rhône valley, ruled from Sion. In 1337 Bishop Aymon governed the Valais.

The Seven Tithings of Upper Valais burned Tourbillon Castle in 1417 and gained civil jurisdiction by the Treaty of Naters in 1446. The Valais rejected the Reformation, but in 1634 the bishop ceded temporal power to the Republic of the Seven Tithings. French invasion ended the old order in 1798; after the Rhodanic Republic and French annexation, the Valais joined Switzerland in 1814.