Mandate of Heaven
During the Five Dynasties and Ten Kingdoms Period, there was no dominant Chinese dynasty that ruled all of China. This created a problem for the Song dynasty that followed, as they wanted to legitimize their rule by claiming that the Mandate of Heaven had passed on them. The scholar-official Xue Juzheng compiled the "Old History of the Five Dynasties" (五代史) during the 960s and 970s, after the Song dynasty had taken northern China from the last of the Five Dynasties, the Later Zhou. A major purpose was to establish justification for the transference of the Mandate of Heaven through these five dynasties and thus to the Song dynasty. He argued that these dynasties met certain vital criteria to be considered as having attained the Mandate of Heaven despite never having ruled all of China. One is that they all ruled the traditional Chinese heartland. They also held considerably more territory than any of the other Chinese states that had existed conterminously in the south. When the Mandate of Heaven gave Zhou the ruling authority they had to figure out how to govern.