Wikipedia
Isarkreis
The Isarkreis (German: Isar District) was one of the 15 administrative districts (German: Bezirke or Regierungsbezirke) of the Kingdom of Bavaria between 1806 and 1837. It is named after its main river, the Isar. It was the predecessor of the Regierungsbezirk Oberbayern (Administrative District of Upper Bavaria).