Abstract: | ![]() Since Tuoba clan came in and ruled the Central Plains in the 4th and 5th centuries, the social economy underwent slowly the transition from the slavery to the feudalism. Upon the unification of northern China on whole, the Northern Wei Dynasty failed in attacking the Song Dynasty in A. D. 451. It caused Northern Wei's social economy itself to change rapidly from the predatory type into the agricultural type ,thereby intensified the social tensions. In order to mitigate the tensions, to promote the the agricultural production, and to strengthen the political power, Emperor Xiaowen Di put the system of land equalization into effect. Moreover, other objective conditions contributed to the system too. [ |