Abstract: During the Long March,the Communist Party of China (CPC) for the first time combined Marxist ethnic theory with China's national conditions and the specific reality of ethnic problems,practically formulating and practicing a series of ethnic policies,such as ethnic equality and unity,protection of religious rights,adjustment of the united front objects,training of ethnic cadres,restoration and development of economy and people's livelihood,etc.,which opened a preliminary exploration of the Sinicization of Marxist ethnic theory of CPC.This process promoted the Party's ethnic theories and policies from "dogmatism" to "seeking truth from facts",and realized the transformation of Marxist ethnic theory from "copying" to "combining with Chinese reality".Based on the interpretation of the principle of dialectical unity of struggle and identity of Marxist class relations,the CPC timely adjusted the object of the united front policy and followed the principle of unity and struggle to unite with the upper echelons of nationalities and religions,showing the truth of Marxist materialist dialectics.The Long March deepened the Party and the Red Army's understanding of the domestic ethnic minorities and prompted the CPC to sublimate from perceptual to rational understanding of the national conditions of unifying a multi-ethnic country.

Key words: the Communist Party of China, the Long March, ethnic theory, ethnic policy, Sinicization, the united front