The map, embracing today’s Croatia, Bosnia, and parts of Montenegro and Serbia, shows the alleged population of Croats in those regions, according to the demographic statistics of 1931.
The map was published with a book Narod i zemlja Hrvata (Nation and Land of Croatians) by Mladen Lorković (1909-1945) in 1939, on the eve of WW II, when Croatia became an independent state, collaborating with Germany and annexing the territory of Bosnia and parts of Serbia. These borders corresponded the idea if the “Greater Croatia”, emphasising the ethnicity of those Croats living outside Croatia.
Lorković, who supported the idea of the Greater Croatia, became Foreign Minister and Minister of Interior of the Independent State of Croatia during WWII. After an attempt to establish a coalition with the Allies, he was removed from his position and executed by the Croatian government in April 1945.