The borders of the present-day nation-states of Southeast Asia took shape during the colonial era, particularly the nineteenth and early twentieth centuries. Nationalist ideologies emerged in the Philippines towards the end of the nineteenth century and a couple of decades later in several other colonies in Southeast Asia, particularly in Burma, Indonesia and Vietnam. Inspired by nationalist movements in Europe and other parts of Asia, Western-educated Southeast Asian intellectuals began to formulate nationalist ideologies, mixing indigenous traditions with transnational influences, including from European and Chinese nationalism and critical Marxist analyses of imperialism. Anti-colonial resistance was an important part of Southeast Asian nationalism, but the nationalists’ goals were more far-reaching, seeking not only national independence but also emancipation from traditional forms of inequality, oppression and injustice, as well as political equality for men and women. Although the efforts to build peaceful, prosperous and socially just nations often were frustrated after independence, the region’s nation-states have proven remarkably resilient, largely because of the continued relevance of the national projects that were launched in the late colonial period.