Bohemia ( boh-HEE-mee-ə; Czech: Čechy [ˈtʃɛxɪ] ; German: Böhmen [ˈbøːmən] ) is the westernmost and largest historical region of the Czech Republic. In a narrow, geographic sense, it roughly encompasses the territories of present-day Czechia that fall within the Elbe River's drainage basin, but historically it could also refer to a wider area consisting of the Lands of the Bohemian Crown ruled by the Bohemian kings, including Moravia and Czech Silesia, in which case the smaller region is referred to as Bohemia Proper as a means of distinction.
https://en.wikipedia.org/wiki/Bohemia