Anti-Imperialism (a Maoist site) has a good article on the roots and development of imperialism and neo-liberalism.
Capitalism is a system that is inherently based on exploitation, and from its beginnings in Western Europe it has been forcefully expanded to cover the entire world. In this process of capitalist globalization, which should be understood as imperialism, the core nations have became wealthy and developed by exploiting and underdeveloping the peripheral countries of the Third World. The superprofits derived from this relationship have enabled imperialism to buy off First World workers through superwages and various other mechanisms, making the core nation working-classes a global labor aristocracy. Globalization has created great inequalities between the rich and poor within nations, but more decisively, it has created greater inequalities between nations which allow all citizens of the wealthy nations to enjoy living standards way above what they would without imperialism.