Excerpts from Books and Wikipedia
"After the Fall of the Tang dynasty, rival warlords ruled China for several decades. In 960, one of those warlords rose to power after his men proclaimed him emperor. . . . When Chao K'uang's brother replaced him on the throne and the Song dynasty continued, the realm would be marked by a reliance on a huge civil bureaucracy. . . . With a stable government, the Song reunified most of China, but its empire was never as extensive as those of earlier dynasties." [National Geographic Almanac, p. 134]
"Alien rule began with the rise of the Qidan (...), who maintained an empire for more than two centuries (916-1125) over parts of north China, Manchuria, and Mongolia. . . . the Liao empire, as it called itself . . . " [Fairbank: China, p. 97-100] "From their founding in 960 the Song had had their capital at Kaifeng on the Yellow River at the head of the Grand Canal, but by 1126 the Jin attacks forced them to abandon North China." [Fairbank: China, p. 115] "Looking ahead, we may posit that the dynasties of conquest--Liao, Jin, and Yuan--form a connected sequence of incursions of Inner Asian military power into China and must be viewed as a single, if sporadic process." [Fairbank: China, p. 118-9]