The practice of transnational feminism networks, in which feminists started exchanging ideas and collaborating across nation-state borders, originated from the United Nations conferences in the 1970s. In 1975 the United Nations Decade of Women began with the United Nations declaration of an International Women's Year. This ushered in a decade of conferences that would continue to the present. Important events during this period included conferences in Mexico City (1975), Copenhagen (1980), Nairobi (1985), and Beijing in 1995.