What assumptions are made by colonials about the native peoples?

In Wole Soyinka's play "Death and the King's Horseman" the
colonials, best represented by the character of Simon(and his wife Jane) Pilkings, does
not understand the culture or the people of the African colony where he has been sent to
govern.  He, and the other British citizens there, are convinced that their ways are
civilized and that anyone should want to adopt those ways and customs. He does not
understand their traditions or their religious beliefs or that they can believe as
strongly in their own way of life as the British do in theirs. Moreover, he insults them
by making a mockery of their traditional dress and cultural practices. Soyinka is
demonstrating what actually happened to the peoples that the British conquered. It was
always their assumption that the natives ought to be grateful and would be happy to give
up their barbaric lives and traditional practices for the ways of the
Empire.