This is a postal stationery of the North German Confederation / Norddeutscher Postbezirk sent in 1870 from Heydekrug (now Šilutė, Lithuania) to Kinten (now Kintai, Lithuania), both located in Memelland. Actually "Norddeutscher Postbezirk" is the name for the postal area of the North German Confederation and not the state itself (it is officially: Norddeutscher Bund). Memelland was part of the Kingdom of Prussia which formed the Confederation in 1866 issuing their own stamps until 1870 before becoming the German Reich when the remaining southern Germanic states joined as well.
Heydekrug was the second largest town in Memelland and it has an interesting origin. According to Wikipedia, a guy named Georg Tallat purchased an inn together with the land and the fishing rights in 1511. "Heide" meaning: heathland and "Krug" meaning: inn, combining together in one word: Heydekrug.
