Saṃghabhadra
Saṃghabhadra (5th century CE, Sanskrit: संघभद्र, Ch. 僧伽跋陀羅・衆賢, Japanese: Sōgyabaddara or Shugen): was an Indian scholar monk of the Sarvāstivāda Vaibhāṣika and  "undoubtedly one of the most brilliant Abhidharma masters in India". Born in Kashmir, he was a contemporary of the Buddhist philosopher Vasubandhu. According to K.L. Dhammajoti, his work forms the most mature and refined form of Vaibhāṣika philosophy. His two main works, the *Nyāyānusāra (Shun zhengli lun 順正理論, "In Accordance with the Truth") and the *Abhidharmasamayapradīpikā (Apidamo xian zong lun 阿毘達磨顯宗論), are very important sources for late Vaibhāṣika thought. He is referenced by various important Buddhist figures, such as Xuanzang, Kuiji, Sthiramati, and Śāntarakṣita who see him as the most authoritative of the Vaibhāṣika Abhidharmikas. Saṃghabhadra's philosophical work was primarily an attempt to defend the orthodox doctrines of the Vaibhāṣika school from the attacks of its main opponents, the Sautrantikas, especially Vasubandhu who had written the Abhidharmakośabhasya as an exposition as well as a critique of many Vaibhāṣika doctrine. Saṃghabhadra is said to have spent 12 years composing the Nyāyānusāra (a commentary to Vasubandhu's verses) to refute Vasubandhu and other Sautrāntikas such as the elder Śrīlāta and his pupil Rāma. According to Xuanzang's records, after composing his works, Saṃghabhadra sought out Vasubandhu in order to face him in public debate, but he died before he was able to do so. 