Its composition led to the founding of a new doctrinal school, called Vaibhāṣika ("those [upholders] of the Vibhāṣā"), which was very influential in the history of Buddhist thought and practice.
Vibhāṣā is a Sanskrit term—derived from the prefix vi + the verbal root √bhāṣ, "speak" or "explain"—meaning "compendium", "treatise", or simply "explanation".
The Mahā-prajñā-pāramitopadeśa (which actually refers to the Aṣṭaskandha) states that 100 years after the Buddha's demise, there arose doctrinal disputes among the great masters, giving rise to distinctly named schools.
This includes the discussion of basically every doctrinal issue of the day, as put forth by: other—non-Sarvāstivādin—Buddhist schools, such as the Vibhajyavāda, the Pudgalavāda, the Mahāsāṃghika, and others; non-Buddhist systems, such as the Saṃkhya, the Vaiśeṣika, and others; and, finally, the Sarvāstivāda itself, as represented by the works of various learnèd and venerable leaders therefrom.
Due to the above two reasons, the Vibhāṣā literature is particularly useful not only in understanding the Sarvāstivāda, but also in obtaining a relatively detailed perspective on the then-current state of both the Buddhadharma and other, non-Buddhist religions.
Some scholars believe that some of the other, now-lost Vibhāṣā texts may have represented a similar authoritative work, as held by the Gandhāra Sarvāstivāda or other centers of orthodoxy.
[5] It was due to the predominance of this text and its teachings at the time that Vasubandhu engaged in the study thereof, as a compendium that encompassed all of the essential doctrines.