Silesian Lowlands

Silesian Lowlands (or Silesian Plains, Polish: Nizina Śląska, Czech: Slezská nížina, German: Schlesische Niederung, Schlesische Tiefebene, Schlesische Bucht or Oderebene) are lowlands located in Silesia, Poland and the Czech Republic. It is part of the North European Plain. Silesian Lowlands is a physical-geographical macroregion. It is the warmest region in Poland.

...
Wikipedia