The earliest known written records of the history of China date from as early as 1250 BC, from the Shang dynasty, during the king Wu Ding's reign, who was mentioned as the twenty-first Shang king by the same. Ancient historical texts such as the Book of Documents, the Records of the Grand Historian and the Bamboo Annals mention and describe a Xia dynasty before the Shang, but no writing is known from the period, and Shang writings do not indicate the existence of the Xia. The Shang ruled in the Yellow River valley, which is commonly held to be the cradle of Chinese civilization. However, Neolithic civilizations originated at various cultural centers along both the Yellow River and Yangtze River. These Yellow River and Yangtze civilizations arose millennia before the Shang. With thousands of years of continuous history, China is one of the world's oldest civilizations and is regarded as one of the cradles of civilization.
