Kushan Period rice in the Amu Darya Basin: Evidence for prehistoric exchange along the southern Himalaya

The origins and prehistoric spread of rice agriculture between East and West Asia are hot topics in the current archaeological community. In this study, we present the results from a preliminary archaeobotanical study at the Khalchayan site in Uzbekistan, where we recovered the oldest securely dated rice thus far identified in Central Asia. We directly dated the rice grains to 1714-1756 cal yr BP (Kushan period), and morphologically compared them with other contemporaneous cultivated rice remains from China and India. The morphological results showed that the rice remains found at Khalchayan are more similar to cultivated japonica rice from southern China and northwestern India. Integrated archeological and chronological results from the surrounding area show that the rice remains found at Khalchayan likely spread along a southern Himalayan route from southwest China to northern India and finally reached the Amu Darya. The rice remains from Khalchayan are the first directly dated and well-reported rice remains found in Central Asia. By the Islamic period, rice was an important culinary aspect of the culture in Central Asia, but the cultural affinity towards rice only developed over the past two millennia. This study provides new information on the spread of rice agriculture globally, especially in arid-semiarid inland regions.