There is no consensus among modern scholars as to when Chinese thought started and whether or not the philosophical ideas of Chinese people originated from a single source. According to traditional beliefs, Chinese culture started with the invention of the diagrams or ideographical symbols by a legendary figure Fu Xi, and was continually shaped through the working of cultural heroes and legendary sage kings, particularly the Yellow Emperor (Huang di), Yao, Shun, and Yu, who are believed to have been the leaders of China in the fourth to third millennia B.C.E. It is traditionally believed that the period of cultural heroes was followed by the three dynasties—Xia (c. 2205–c. 1600 B.C.E.), Shang (c. 1600–c. 1045 B.C.E.), and Zhou (c. 1045–256 B.C.E.)—in which a reasonably comprehensive system of thought about the philosophical foundation of the world developed and that the earliest writings discovered so far as presented in "oracle bone inscriptions," recording royal divinations and major natural and political events in the early part of the Shang dynasty, mark the beginning of systematic thinking concerning political, religious, and philosophical matters. Modern scholarship on ancient China and new findings of regional centers of civilization, however, have challenged the traditional convictions about the actual existence and functioning of the Xia dynasty and about a single line of development in early Chinese thought. Symbols and preliminary pictographs on potteries and jades discovered in East and South China (Longshan culture), and jade wares and bronze figures and masks found in Southwest China (Shu culture), have shed a new light on the multioriginal sources of Chinese thought, and on the ways these sources were integrated into a single culture through a long and gradual process. Archaeological excavations of houses, cities, and sacrificial sites dated to the prehistorical period also prove that well before using characters to record their thinking of the world and life, the people who lived in the land of China had started to reflect on the physical and the metaphysical world, search for the harmonious interaction between the spiritual and the mundane, and implement these ideas in construction, decoration, and in a variety of economic, political, and religious activities.