- Europe
Reunification of Northern Schleswig
Northern Schleswig came under Danish sovereignty on 15 June 1920, marked by King Christian X's ceremonial ride across the old frontier; the boundary then fixed remains the Danish-German border today.
Era: The Schleswig Question and the Making of the Modern Border
Sources: The reunification of Denmark in 1920 · nordics.info (Aarhus University)
- Asia
Abdullah founds the Emirate of Transjordan
After the Cairo Conference, Abdullah ibn Hussein formed a government east of the Jordan under British mandate, establishing Hashemite rule and the Emirate of Transjordan.
Era: The Arab Revolt, the Emirate of Transjordan and Independence
Sources: Abdullah I: Biography, History, and Assassination · Encyclopaedia Britannica, Jordan: Transjordan, the Hashemite Kingdom, and the Palestine war · Encyclopaedia Britannica
- Europe
Founding of the Soviet Union
The Russian, Ukrainian, Belarusian, and Transcaucasian Soviet republics formally unite to create the Union of Soviet Socialist Republics, a federal one-party communist state with its capital at Moscow.
Era: Revolution and the Fall of the Romanovs
Sources: Soviet Union · Encyclopaedia Britannica, Russia · Encyclopaedia Britannica
- Asia
Mongolian People's Republic proclaimed
After the death of the Bogd Khan in May 1924, the monarchy lapses and the Mongolian People's Republic is proclaimed in November, the world's second socialist state and a satellite of the Soviet Union.
Era: Independence, Revolution, and the People's Republic
Sources: Mongolia: Independence and revolution · Encyclopaedia Britannica, Bogd Gegeen Khan · Encyclopaedia Britannica
- Europe
Signing of the Lateran Treaty
The Holy See and Italy signed the Lateran Treaty, signed by Mussolini for Italy and Cardinal Gasparri for the papacy, recognising the Holy See's sovereignty and creating the State of Vatican City.
Era: The Lateran Treaty and the Birth of Vatican City
Sources: Lateran Treaty · Encyclopaedia Britannica, How the Vatican Became a Country · EWTN Vatican
- Europe
The State of Vatican City comes into being
With the exchange of ratifications on 7 June 1929 the State of Vatican City formally came into existence as an independent sovereign state of about 44 hectares.
Era: The Lateran Treaty and the Birth of Vatican City
Sources: Lateran Treaty · Encyclopaedia Britannica, How the Vatican Became a Country · EWTN Vatican
Formation in the 1920s
Every event in the Terralore archive tagged formation — origins, unifications and the founding of states as each nation's archive records them, narrowed to the 1920s — 6 of them, drawn from 5 nations, running from 1920 to 1929. Each entry keeps the sources it was verified against and links back to the chronicle it came from.
- Events
- 6
- Nations
- 5
- Earliest
- 1920
- Latest
- 1929
- Europe
- 4
- Asia
- 2
Every entry below is the same record, with the same sources, as the one on its nation’s chronicle.