Fazang (法藏) discusses the doctrinal classification of the Three Periods (三時教説, hereafter, Three Periods Theory) of Jiexian (戒賢) and Zhiguang (智光) in detail in his Huayan-jing Tanxuan-ji. As the Mind-Only theory of Tang China based on Xuanzang’s (玄奘) new translations (新訳唯識) is regarded as a succession of Jiexian’s ideas, Jiexian’s Three Periods Theory discussed by Fazang has generally been seen as a theory of doctrinal classification (判教) of the Mind-Only school based on the new translations. However, this paper will show that from an examination of the Wuzixingxiang chapter (無自性相品) of the Saṃdhi-nirmocana Sūtra (hereafter, SNS), in which the Mind-Only school’s Three Periods Theory has its roots, there are reasons to believe that the school’s aim in expounding this theory was not exactly as Fazang laid out in his treatise. Through an analysis of how the Mind- Only school based on the new translations understood the teaching of the Threefold Turning of the Wheel of Dharma (三轉法輪説) in the SNS, the author will argue that the school understood the teaching not as an attempt at doctrinal classification but rather as a theory of Mahāyāna practice based on the teachings of non-existence of self-nature (niḥsvabhāva). This paper will illustrate the originality of Fazang’s rendering of the Three Periods Theory and how it contributed in turning the Threefold Turning of the Wheel of Dharma theory in the SNS into one with strong overtones of doctrinal classification which is a unique aspect of the Chinese Buddhist tradition and Buddhism in East Asia.