The Sudetes or Sudetes Mountains (in Polish and Czech Sudety, which is a plural proper noun) is a mountain range in Poland and the Czech Republic. In Czech, the word "Sudety" or its English equivalent refers to a much broader region Sudetenland, which includes basically all area in Bohemia near the border with Germany and Austria. If referring this region to a Czech person, it is probably better to use term Sudetes Subprovice (Krkonošsko-jesenická subprovincie) or not referring to this region at all and use the names of mountains that is consists of.
From west to the east:
Poland:
From west to the east:
Czech Republic: