Imperialism can be understood as the doctrine that holds the dominion of some nations over others. There are imperialisms since empires have existed since antiquity, but there is a current tendency to limit as "imperialism" the process of economic expansion that took place in Europe in the mid-nineteenth century, especially after 1870, and this was known as free trade imperialism. During this period, many European countries, especially Great Britain, expanded, first unofficially and later annexed territories and formed colonies in Africa, Asia and the Pacific. Other European colonial powers joined Great Britain, in Africa most of the territory shared with France.