Influence from the west: from wheat to wheels
The same general era which witnessed the florescence and decline of several regional complex societies of the advanced Neolithic was also the period when central China came into contact via trade with Central Asia, facilitating the adoption of domesticates and other technology from the west.
Uncertainty remains over how early broomcorn millet appears in Western Eurasia as well as the east. From the third millennium bce, however, the presence of Chinese millets beyond China was paralleled by the eastwards spread of crops and livestock, notably wheat and barley, and cattle and sheep, into China. This era has been referred to as one of Bronze Age globalization,[678] and in the northwestern parts of India and Pakistan as a ‘Chinese Horizon', as several plants of Chinese origin appear to have arrived around or just after 4,000 years ago, including millets, japonica rice, peach, apricot, and hemp.[679] An important Central Asian site with evidence relating to these Old World crop dispersals is Begash in Kazakhstan, with direct dates on wheat and broomcorn millet that fall between 2450 and 2150 cal bce.[680]Within China, wheat mostly dates from 2000 bce onwards, although earlier dates are known. A single radiocarbon date from the Zhaojiazhuang site in Shandong province places bread wheat in China at 2500-2270 cal bce,[681] currently the oldest record of a Southwest Asian crop in China.[682] During the course of the Han dynasty the adoption of rotary querns allowed the development of flour foods like noodles and buns.
This same period provides the first clear evidence for domesticated sheep, goats, and cattle, which were also likely introduced from the west around 4,500 years ago.[683] Unlike in Western and Central Asia (including Xinjiang) or India, there are no ethnographic or historical traditions of major reliance on dairying these animals in central China.[684] During the course of the second millennium bce, other technologies moved eastwards across the continent, including bronze metallurgy by c.
2000 bce and horses, wheels, and chariots by 1200 bce.[685]The second millennium bce sees a substantial increase in evidence of Southwest Asian crops in China as well as in Central Asia.[686] During this period, wheat and barley are frequently reported from dated contexts in western China, including in Gansu and Qinghai provinces and Xinjiang and Tibet autonomous regions.[687] Evidence from western Yunnan at the site of Haimenkou and in southern Tibet at Changgougou (on the Yarlung Tsangpo River) indicates the presence of wheat and/or barley by perhaps as early as c. 1400 bce, but certainly by c. 1000 bce.[688] This early episode of food globalization, linking east to west through crop exchanges, is mirrored in the south by increased contacts between the Yangtze, southernmost China (Lingnan), and Southeast Asia, by which rice and millets spread southwards.