And my point is its not a "NEW" name, just an alternate one.
The country has been traditionally divided into three lands, namely Bohemia (Čechy) in the west, Moravia (Morava) in the east, and Czech Silesia (Slezsko; the smaller, south-eastern part of historical Silesia, most of which is located within modern Poland) in the northeast.[27] Known as the lands of the Bohemian Crown since the 14th century, a number of other names for the country have been used, including Czech/Bohemian lands, Bohemian Crown, Czechia, and the lands of the Crown of Saint Wenceslaus. When the country regained its independence after the dissolution of the Austro-Hungarian empire in 1918, the new name of Czechoslovakia was coined to reflect the union of the Czech and Slovak nations within one country.
My emphasis added.