Dependency theory is the notion that resources flow from a "periphery" of poor and underdeveloped states to a "core" of wealthy states, enriching the latter at the expense of the former. A central contention of dependency theory is that poor states are impoverished and rich ones enriched by the way poor states are integrated into the "world system". This theory was officially developed in the late 1960s following World War II, as scholars searched for the root issue in the lack of development in Latin America. The theory arose as a reaction to modernization theory, an earlier theory of development which held that all societies progress through similar stages of development, that today's underdeveloped areas are thus in a similar situation to that of today's developed areas at some time in the past, and that, therefore, the task of helping the underdeveloped areas out of poverty is to accelerate them along this supposed common path of development, by various means such as investment, technology transfers, and closer integration into the world market. Dependency theory rejected this view, arguing that underdeveloped countries are not merely primitive versions of developed countries, but have unique features and structures of their own; and, importantly, are in the situation of being the weaker members in a world market economy. Some writers have argued for its continuing relevance as a conceptual orientation to the global division of wealth. Dependency theorists can typically be divided into two categories: liberal reformists and neo-Marxists. Liberal reformists typically advocate for targeted policy interventions, while the neo-Marxists believe in a command-centered economy. History Dependency theory originates with two papers published in 1949, one by Hans Singer and one by Raúl Prebisch, in which the authors observe that the terms of trade for underdeveloped countries relative to the developed countries had deteriorated over time: the underdeveloped countries were able to purchase fewer and fewer manufactured goods from the developed countries in exchange for a given quantity of their raw materials exports. This idea is known as the Prebisch–Singer thesis. Prebisch, an Argentine economist at the United Nations Commission for Latin America (UNCLA), went on to conclude that the underdeveloped nations must employ some degree of protectionism in trade if they were to enter a self-sustaining development path. He argued that import-substitution industrialisation (ISI), not a trade-and-export orientation, was the best strategy for underdeveloped countries. The theory was developed from a Marxian perspective