Anarcho-capitalism first emerged in the 1970s and 1980s, partly due to growing criticism in the west of government regulation of capitalism and a revival of interest in free market economics. Closely associated with, but different from, libertarianism, anarcho-capitalism has been championed by US economists Murray Rothbard (1926-95) and David Friedman (1945-). Rothbard first used the term ‘anarcho-capitalism’ to categorise his own ideas and argued that they were based on three specific ideological traditions – 19^th century classical liberalism, 19^th century US individualist anarchism and the 20^th century Austrian school of economics.