Radiocarbon dating bronze
Three dates from the Western Zhou and Eastern Zhou periods were also obtained from samples from Baligang, Wangchenggang and Dong’gao.
Even at the Bronze Age sites, obvious evidence of intrusion can still be found, such as the historical dates obtained from apparent Shang dynasty levels at the Shangguancun site and the Western Zhou levels at Donggao (ESM 2).7,920 seeds from more than 38 taxa were identified in 690 samples, comprising cereals, fruits and field weeds (ESM 1).
Therefore, direct dates from ancient wheat grains should provide fundamental information from which to begin an assessment of the actual role of wheat in the subsistence systems of late Neolithic central China.
Towards this end, the present paper reports the results of systematic archaeobotanical work at the Xiazhai site in central China and direct dates on wheat grains from there and from another three sites in central China (Fig. Together with direct dates on late Neolithic wheat grains from some other sites elsewhere in China and a review of early wheat reports without direct dates, we offer an updated assessment of the timing of wheat adoption in central China and its role in the latest Neolithic to early Bronze Age there. Various kinds of features, such as storage pits (secondarily refilled with occupational refuse), houses, a moat, burials and kilns were discovered from different periods at this site, providing a very rich archaeological sequence.
For the Shijiahe samples, the charred rice grain from the context H2497 yielded a date calibrated to 2487–2291 .
Based on systematic archaeobotanical data and direct dating of wheat remains from the Xiazhai site in central China, as well as a critical review of all reported discoveries of Neolithic and Bronze Age wheat from this region, we conclude that many wheat finds are intrusive in Neolithic contexts.Flotation samples for archaeobotanical analysis were collected from 690 contexts from different periods, during excavation at the Xiazhai site.7,000 l of soil samples were floated at the site by the wash-over bucket flotation method (Pearsall ).The first hypothesis argues that wheat was brought from Central Asia through Xinjiang and then diffused from west to east within China, following the path of the traditional Silk Road (Li ).The second suggests a route by the steppes north of the Tian Shan mountains and into the Hexi corridor via the Heihe river (Black river), and from there westwards into Xinjiang and eastwards into the middle and lower Huang He (Yellow river) valley (Flad et al. A variant of this hypothesis offers to explain the nearly synchronous appearance of wheat in western, central and eastern parts of northern China.