Xu Qianxue, Zizhi Tongjian Houbian (17th century) Vol. 141-142. Zhejiang University Copy p. 42 of 124 „欽察部去中國三萬餘裏夏夜極短日蹔沒輙出土産良馬富者以萬計俗祍金革勇猛剛烈青目赤髪“ en. „The Kipchak tribe is situated at a distance of over 30,000 li from China. In summer, the evening is extremely short; the sun temporarily sets then immediately rises. Their soil produces good horses, that the rich people count by ten thousands. They customarily sleep armed and armored; they are courageous, fierce, firm, and vehement; [they are] blue/green-eyed and red-haired“. Note: the expression „祍金革“ lit. „to lie/to sleep with metal and leather > to sleep armed and armored“ is not to be taken literally; it is a Chinese literary trope about the northerners' supposedly rugged and hardy nature; e.g. Liji„Zhong Yong“ quote: „衽金革，死而不厭，北方之強也，而強者居之。“, tr.: „To sleep armed and armored, to die undismayed; those are strengths in the north, the forceful dwell there.“
