Civilizations in Asia arose in several places at once. As in the Mediterranean, the earliest civilizations coincided with the geography of the Neolithic Revolution. Despite archaeological excavations indicating an advanced civilization between 2100 and 1600 BCE, many historians regard the earliest known dynasty in China, the Xia, as mythological due to lack of written records and an oral tradition influenced by subsequent dynastic conflicts. The class structure of the Shang Dynasty was comprised of the king and nobles, a military class, craftspeople, and peasants. Under the Zhou Dynasty, successor to the Shang, emperors formulated the idea of the “Mandate of Heaven” in which the right to rule was the product of the moral authority of the king or queen, and heaven imbued the ruling dynasty with both the right to rule and the obligation to protect the best interests of the kingdom as a whole.