The Eastern Neisse,[1] also known by its Polish name of Nysa Kłodzka (German: Glatzer Neiße, Czech: Kladská Nisa), is a river in southwestern Poland, a left tributary of the Oder, with a length of 188 km (21st longest) and a basin area of 4,570 km2 (3,742 in Poland).

This would have meant that (East) Germany could have retained approximately half of Silesia, including most of Wrocław (formerly Breslau).

However the Soviets rejected the suggestion at the Potsdam Conference and insisted that the southern boundary between Germany and Poland be drawn further west, at the Lusatian Neisse,[3][1] in some way reintroducing the border to the place from the beginnings of Polish statehood, i.e. west of Legnica Town, important for Bolesław IV the Curly and Henry the Bearded, two Polish Princepses.

[4][5] The Eastern Neisse originates in the Králický Sněžník Mountains of the Sudetes, near the border with the Czech Republic.

The river has often burst its banks and flooded nearby towns, at times destroying them completely.