An unusual and interesting postcard map of the Kingdom of Hungary, showing how it was divided by the Treaty of Trianon in 1920.

The Treaty of Trianon was imposed upon Hungary by the Allied powers after the First World War. The Kingdom of Hungary was half of the Austro-Hungarian empire, one of the principal combatants. The Treaty of Trianon reduced the area of the country by 71.4%, and its population by 64%. Hungarian leaders were forced to accept the Allied terms and did so under duress.

This drastic reordering of the area was driven by the principle of self-determination of peoples, in an attempt to give all non-Hungarians their own national states.