Historically, racism was a major driving force behind the Transatlantic slave trade. It was also a major force behind racial segregation, especially in the United States in the nineteenth and early twentieth centuries, and South Africa under apartheid; 19th and 20th century racism in the Western world is particularly well documented and constitutes a reference point in studies and discourses about racism. Racism has played a role in genocides such as the Armenian genocide, and the Holocaust, and colonial projects like the European colonization of the Americas, Africa, and Asia. Indigenous peoples have been – and are – often subject to racist attitudes. Practices and ideologies of racism are condemned by the United Nations in the Declaration of Human Rights.