 In the fourth century, Vasubandhu undertook a comprehensive survey of the Sarvāstivāda School’s thought, and wrote a compendium, Treasury of Knowledge, (Abhidharmakośakārikā [AK]; Mngon pa ku 1b–25a) with his own Commentary on the Treasury of Knowledge (Abhidharmakośabhāṣya [AKB], Mngon pa ku 26b–258a). This commentary not only offers an excellent account of the Sarvāstivādin views, including the theory of the two truths, but also offers a sharp critique of many views held by the Sarvāstivādins. Vasubandhu based his commentary on the Mahāvibhāṣā (The Great Commentary), as the Sarvāstivādins held their philosophical positions according to the teachings of the Mahāvibhāṣā. Consequently, Sarvāstivādins are often known as Vaibhāṣikas.