What was the purpose of the items being buried with the dead person?

In many cultures - ancient Egyptian or Chinese, for example - the dead weren't "gone" completely; they had crossed into a different plane or realm of existence, and they would continue to need physical things from the "real" world.

In Egypt, food and wine were placed in the tombs so that the deceased would have food for their next journey. In China, paper replicas of the physical goods were burned, and the smoke of the paper image would serve as the real item in the afterlife.