Pollen,plant seeds and phytoliths from an AMS dated sediment profile at the Xishanping site indicate that the cultivation of rice might start no later than 5070 cal.a BP in the region of Tianshui,Gansu Province.It continued from 5070 to 4300 cal. BP.This is so far the oldest and the most northwestern record of cultivated rice in Neolithic China,which extends the known region of prehistoric rice cultivation at least 2° longitude to the west.This finding provides important evidence for reconstructing the cultivation region of rice at 5000 a BP (an important time period),and its spreading history in East Asia,during the Neolithic.