The Abhidharmakośabhāsya (, lit. Commentary on the Sheath of Abhidharma), Abhidharmakośa () for short (or just Kośa or AKB), is a key text on the Abhidharma written in Sanskrit by the Indian Buddhist scholar Vasubandhu in the 4th or 5th century CE. The Kośa summarizes the Sarvāstivādin Abhidharma in eight chapters with a total of around 600 verses and then comments on (and often criticizes) it. This text was widely respected and used by schools of Buddhism in India, Tibet and East Asia. Over time, the Abhidharmakośa became the main source of Abhidharma and Sravakayana Buddhism for later Mahāyāna Buddhists. In the Kośa, Vasubandhu presents various views on the Abhidharma, mainly those of the Sarvāstivāda-Vaibhāṣika, which he often criticizes from a Sautrāntika perspective. The Kośa includes an additional chapter in prose refuting the idea of the "person" (pudgala) favoured by some Buddhists of the Pudgalavada school. The Vaibhāṣika master Samghabhadra considered that Vasubandhu had misrepresented numerous key points of Vaibhāṣika Abhidharma in the Kośa, and saw Vasubandhu as a Sautrāntika (upholder of the sutras). However, Vasubandhu often presents and defends the Vaibhāṣika Abhidharma position on certain topics (contra Sautrāntika). Because of this, Chinese commentators like Pu Guang do not see Vasubandhu as either a Vaibhāṣika nor as a Sautrāntika. Background The Abhidharmakośabhāsya (AKB) is a work of Abhidharma, a field of Buddhist philosophy which mainly draws on the Sarvāstivāda Abhidharma tradition. This tradition includes various groupings or "schools", the two main ones being Vaibhāṣika and Sautrāntika. The main source for the Vaibhāṣika tradition (which was based in Kaśmīra) is the Abhidharma Mahāvibhāṣa Śāstra. The other main tradition of Sarvāstivāda philosophy were those masters who were called "westerners" (Pāścāttya) or "outsiders" (Bāhyaka) and they were mainly based in Gandhara. These masters (later known as Sautrāntikas) did not fully accept the Vaibhāṣika philosophy and compiled their own Abhidharma texts, such as the Abhidharma-hṛdaya by Dharmaśrī, which was the first Abhidharma text to provide a series of verses with prose commentary (this is the style that the Kośa follows). This work was very influential on subsequent Abhidharma texts (which imitated its style) and various commentaries were written on it. The Abhidharmakośabhāsya's style and structure is based on these Sautrāntika Abhidharma works. According to K.L. Dhammajoti, in the AKB, Vasubandhu often favors the opinion of the Sautrāntika school against the Sarvāstivāda Vaibhāṣikas (when there is a dispute). For example, he criticizes the doctrine of