buffer state

A small state lying between two or more larger and potentially belligerent states, as a means of reducing border friction between them; often specially created for the purpose, though seldom successful. For example, after World War 1, attempts were made to create a buffer state between Germany and France involving Belgium, the Saar, the Rhine area, and Alsace-Lorraine.

The conception of buffer states is part of the theory of balance of power that entered European strategic and diplomatic thinking in the 17th century. In the 19th century, the manipulation of buffer states like Afghanistan and the Central Asian emirates was an element in the diplomatic "Great Game" played out between Britain and Tsarist Russia for control of the approaches to strategic mountain passes that led to British India.

Other examples of buffer states include:

Qasim Khanate, between Muscovy and Kazan Khanate Mongolia, between the People's Republic of China and Russia Poland following World War I, located between Germany and the Soviet Union North Korea during and after the Cold War, whom some analysts see as a buffer state between the military forces of the People's Republic of China and American forces in South Korea Neutral Austria, Sweden and Finland were buffer states during the Cold War. Belgium before World War I, serving as a buffer between the United Kingdom, France, and Germany Thailand during colonial times, served as a buffer between British India (later Burma) and French Indochina The Rhineland served as a demilitarised buffer-zone between France and Germany during the inter-war years of the 1920s and early 1930s.

The invasion of a buffer state by one of the powers surrounding it will often result in war between the powers. The Carolingian Empire also created some independent duchies in the Pyrenean border acting as buffer states against the Muslim kingdoms, an area called the Hispanic March, giving form to nowadays Catalonia.