Abstract: The boundary between palaeosol S₀ and loess L₀ represents the shift from a phase with strong pedological process to a period of accelerated eolian dust deposition in the Weihe River Basin between the middle and late Holocene.This was caused by an abrupt climatic change from the period dominated by southeastern monsoon to the period dominated by northwestern monsoon.Because of this change, soils have been deteriorated in their fertility, droughts, dust storms, river desiccation and water shortage have been frequent.These affected the nomadism upper and middle reaches, and arable farming of the Predynastic Zhou in the Weihe River Basin.Land-use was, therefore, shifted from arable farming to nomadism in the upper and middle reaches of the basin.Due to the southern migration of the nomadism, the people of the predynastic Zhou of arable farming community was forced to move south to the Guanzhong Basin, and established their capital city "Qiyi" on the Zhouyuan loess tableland.The deterioration of land resouces also caused famine and social instability, and later, the clapse of the Shang Dynasty in the lower reaches of the Yellow River.Due to technical reasons, the S₀/L₀ boundary has not been precisely dated by ¹⁴C or TL dating methods.Each author takes a different age between 3500-2500 a B.P.for the S₀/L₀ boundary and the abrupt monsoonal climatic change represented.Through stratigraphic studies, with consideration of the dates acquired from the palaeosol and the cultural remains around the S₀/L₀ boundary in the loess profiles, and the historical events and the newly published historical timetable of the Xia, Shang and Zhou dynasties, it is concluded that the S₀/L₀ boundary and the monsoonal change represented could be dated to calendar year 1150 B.C.( 3100 a B.P.) or ¹⁴C dating 3030?80 a B.P..This would facilitate the higher resolution studies of the environmental change and the evolution of the human-environment relationship in the Weihe River Basin.It should be noted that there was a period with increased terrestrial dust deposition in the Greenland ice between calendar year 3100 and 2400 a B.P..The change in the atmospheric circulation recorded in Greenland ice could have certain connections with the abrupt monsoonal climatic shift recorded by the S₀/L₀ boundary in the Weihe River Basin which occupies the southern part of the Loess Plateau.