The mandate of heaven is a chinese set of beliefs on how their emperors should be. They believed that the emperor was sent form Heaven and read different sings from nature to be able to dethrone him or revolt agaisnt him, floods, famine and succesful rebelions meant bad signs for the emperors, they didn´t have to be high born, the could be normal people, and they were sent to rule over China by God.
Today, historians generally agree on several main causes of the Korean War, including: the spread of communism during the Cold War, American containment, and Japanese occupation of Korea during World War II.