History of Czechoslovakia (1918–1938)
The First Czechoslovak Republic emerged from the collapse of the Austro-Hungarian Empire in October 1918. The new state consisted mostly of territories inhabited by Czechs and Slovaks, but also included areas containing majority populations of other nationalities, particularly Germans (22.95 %), who accounted for more citizens than the state's second state nation of the Slovaks, Hungarians (5.47 %) and Ruthenians (3.39 %).
Source: Wikipedia — History of Czechoslovakia (1918–1938) (CC BY-SA 4.0)