The appearance of characters is the most important sign that ancient human society entered the civilized era. Hutuluo Book is the beginning of Chinese civilization. The Book of Changes says, "Rivers draw pictures, Luo writes books, and saints write them." The Analects of Confucius says, "If the phoenix does not arrive, the river will not draw." In the Chronicle of Bamboo Books, it is said that the Yellow Emperor built an altar in Heluo and got a book of dragons and turtles.
Taiji diagram is a natural phenomenon at the intersection of the Yellow River and Luohe River, because Taiji diagram is like a whirlpool formed by the intersection of the Yellow River and Luohe River. Through this natural phenomenon, the Terran Fuxi created Tai Chi and Eight Diagrams.