The Fourth World is an extension of the Three-World Model, used variably to refer to
The term is not commonly accepted and "Fourth World" has also been used to refer to other parts of the world in relation to the Three-World Model.
Fourth World follows the First World, Second World, and Third World classification of nation-state status; however, unlike the former categories, Fourth World is not spatially bounded, and is usually used to refer to size and shape which does not map onto citizenship in a specific nation-state. It can denote nations without a sovereign state, emphasizing the perceived non-recognition and exclusion of ethnically- and religiously-defined peoples from the politico-economic world system, such as the First Nations groups throughout North, Central and South America. Spanish sociologist Manuel Castells of the University of Southern California Annenberg School for Communication has made extensive use of the term fourth world.
The term originated with a remark by Mbuto Milando, first secretary of the Tanzanian High Commission in Canada, in conversation with George Manuel, Chief of the National Indian Brotherhood of Canada. Milando stated that "When Native peoples come into their own, on the basis of their own cultures and traditions, that will be the Fourth World."
Since publication of Manuel's The Fourth World: An Indian Reality (1974), the term Fourth World is synonymous with stateless, poor, and marginal nations. Since 1979, think tanks such as the Center for World Indigenous Studies have used the term in defining the relationships between ancient, tribal, and non-industrial nations and modern industrialised nation-states. With the 2007 UN Declaration on the Rights of Indigenous Peoples, communications and organizing amongst Fourth World peoples have accelerated in the form of international treaties between aboriginal nations for the purposes of trade, travel, and security. In the Indian left movement, Dr. M. P. Parameswaran's ideas on the fourth world caused widespread debates, which eventually led to his expulsion from the Communist Party of India (Marxist) in 2004.