The term "Five Dynasties" was coined by Song dynasty historians and reflects the view that the successive regimes based in Kaifeng possessed the Mandate of Heaven. Yet three of these dynasties were founded by barbarian Shatuo Turks, and the Southern regimes generally had more stable and effective government during this period. The Qing historian Wang Fuzhi (1619–1692) wrote that this period can be compared to the earlier Warring States period of ancient China, remarking that none of the rulers could be described as "Son of Heaven". These rulers, despite claiming the status of emperor, sometimes dealt with each other on terms of diplomatic equality out of pragmatic concern. This concept of "sharing the Mandate of Heaven" as "sibling states" was the result of the brief balance of power. After the reunification of China by the Song dynasty, the Song embarked on a special effort to denounce such arrangements.