title: Nation state
context: Belgium is a classic example of a state that is not a nation state. The state was formed by secession from the United Kingdom of the Netherlands in 1830, whose neutrality and integrity was protected by the Treaty of London 1839; thus it served as a buffer state after the Napoleonic Wars between the European powers France, Prussia (after 1871 the German Empire) and the United Kingdom until World War I, when its neutrality was breached by the Germans. Currently, Belgium is divided between the Flemings in the north and the French-speaking or the German-speaking population in the south. The Flemish population in the north speaks Dutch, the Walloon population in the south speaks French or German. The Brussels population speaks French or Dutch.
question: When was Belgium established as a nation state?
answers: 1830