Latvia division. The borders of historical and cultural regions usually are not explicitly defined and in several sources may vary. In formal divisions, Riga region, which includes the capital and parts of other regions that have a strong relationship with the capital, is also often included in regional divisions; e.g., there are five planning regions of Latvia (), which were created in 2009 to promote balanced development of all regions. Under this division Riga region includes large parts of what traditionally is considered Vidzeme, Courland, and Zemgale. Statistical regions of Latvia, established in accordance with the EU Nomenclature of Territorial Units
On the Restoration of Independence of the Republic of Latvia that in April 1920 the Latvian nation followed the principle of self-determination by electing a Constitutional Assembly of Latvia, which adopted the Constitution of Latvia on 15 February 1922, in general, equal and direct elections, based on proportional representation. On 23 August 1939, the Soviet Union and Nazi Germany signed the Molotov–Ribbentrop Pact, which included a secret protocol dividing Eastern Europe into spheres of influence. Latvia was apportioned to the Soviet sphere and on 5 October 1939, signed a mutual assistance pact. On 16 June 1940, the Soviet Union issued an ultimatum to Latvia accusing it of not carrying out