Racism is a creation of the Age of Reason and the early application of science to the explanation of human variability. Until the 15th century, most ofthe people Europeans came into contact with were largely equivalent in technology and social organization (urban, agricultural states with iron metallurgy, writing, kings, guns, etc). They might have been feared, hated, and considered barbarians or heathens, but they were not demonstrably behind Europe in most measures of "civilization". Racism (the notion that certain people were biologically inferior to others - and perhaps even incapable of acheiving high civilization) is a much more recent notion. It originated as a way of explaining the supposedly less advanced cultures and people encountered by European explorers - and borrowed from the biological sciences up to and including Darwinism.
Racisim has been disproven by more recent applications of science, but it is a scientific theory and worldview nonetheless. And it has nothing necessarily to do with hatred, war, conquest, slavery, and genocide. People are perfectly capable of exploiting other people without having to believe they are inferior.