in funeral rituals, similar to what Hung Ling-yu calls the "modern Wal-Mart syndrome". Bronze The oldest bronze object found in China was a knife found at a Majiayao site in Dongxiang, Gansu, and dated to 2900–2740 BC. Further copper and bronze objects have been found at Machang-period sites in Gansu. Metallurgy spread to the middle and lower Yellow River region in the late 3rd millennium BC. Climate changes Scholars have come to the conclusion that the development of the Majiayao culture was highly related to climate changes. A group of scholars from Lanzhou University have researched climate changes during the Majiayao culture and the results indicate that the climate was wet during 5830 to 4900 BP, which promoted the development of early and middle Majiayao culture in eastern Qinghai province. However, from 4900 to 4700 BP, the climate underwent droughts in this area, which may be responsible for the decline and eastward movement of prehistoric cultures during the period of transition from early-mid to late Majiayao culture. The transition from Yangshao to Majiayao coincides, climatically, with the Piora Oscillation. See also History of metallurgy in China List of Neolithic cultures of China Three Sovereigns and Five Emperors Xia dynasty Xishanping Notes References Neolithic cultures of China Bronze Age in China 4th-millennium BC establishments