The Mandate of Heaven is a Chinese idea which is thousands of years old. It was used to explain why some rulers were successful and others were not. Basically, the idea was that if the ruler was doing the right kind of things, like taking care of the people and making sure that justice was being done, then the gods (and heaven) would bring them blessings like a good harvest or other kinds of good luck. But if the ruler was not taking care of the people properly and was not listening to their needs, then they would be punished and the gods would take away their good fortune. So, in a way, the Mandate of Heaven was like a warning to rulers to be kind and just or else they would lose their power.