I think most people have an understanding of colonialism and how colonial powers affected societies which they touched. Whether it was the British in India or the French in Algeria, bringing an imposing force to a distinct people is complicated and often destructive. Colonialism was by nature an intrusion on the native population. The colonist country looked to use the human and natural resources for its own good. This combined with the exotic and mysterious nature of foreign worlds make stories like Heart of Darkness universally understood. Heartbreak, injustice and human nature all collide to make a story like this interesting to a wide audience of varying cultural identities.