The International Agrarian Bureau, commonly known as the Green International, was founded in 1921 by the agrarian parties of Bulgaria, Czechoslovakia, Poland and Yugoslavia. The creation of a continental association of peasants was championed by Aleksandar Stamboliyski of the Bulgarian Agrarian National Union, but originated with earlier attempts by Georg Heim. Following Stamboliyski's downfall in 1923, the IAB came to be dominated by the Republican Party of Farmers and Peasants in Czechoslovakia, whose member Karel Mečíř served as its first leader. Mečíř was able to extend the IAB beyond its core in Slavic Europe, obtaining support from the National Peasants' Party in Greater Romania; as an ideologue, Milan Hodža introduced the Green International to European federalism.

Milan Hodža was a Slovak politician and journalist, serving from 1935 to 1938 as the prime minister of Czechoslovakia. As a proponent of regional integration, he was known for his attempts to establish a democratic federation of Central European states.