In the collection of the Potala Palace, there are preserved sources revealing several different readings of the Abhidharmakośakārikā (AKK) that have doctrinal origins. AKK.V.42-2, which cannot be found in the heretofore available Sanskrit version, or the Tibetan translation, but which corresponds to Paramārtha’s translation of AKK, is presented in this paper. Further, AKK.V.42-1 explains the two reasons why only jealousy and the stinginess are counted among the nine unions from the standpoint of the eight possessions. AKK.V.42-2 explains three new reasons for the10 possessions from the standpoint of the Vaibhāṣika. In contrast, Xuanzang’s translations of the Abhidharmakośabhāṣa (AKBh) and the Nyāyānusāriṇī offer another four reasons, suggesting that the Paramārtha and Xuanzang translations are based on different sources. The information contained in Yaśomitra’s commentary reveals that the Paramārtha’s theory of three causes is the oldest, followed by Sanghabhadra’s theory of one cause. The Xuanzang translation of the AKK adopts the four-cause theory by combining the other two, but because the four-cause theory can be also found in Sthiramati’s commentary, it is not a modification of Xuanzang’s. This study thus reveals the relative ages of the information in the texts related to the AKBh, as well as that the content of the AKBh was constantly updated with the latest doctrines.