Āśvalāyana is one of the exponent-sages of the five branches of Ṛgveda. Through the Guru- Śiṣya tradition, according to the manner of recitation, way of reading and difference in pronunciation, several branhces of the Veda have emerged. The branches are named after the pioneer-sage. In case of Ṛgveda, Sage Śākala was the first to study Ṛksaṁhitā. After that, four other sages — Śāṁkhyāyana, Āśvalāyana Maṇḍūka and Vāskala studied the same, yet maintaining the distinguishing factors of their own spatial and temporal conditions.
In the commentary of Caraṇavyūhasūtra by Śaunaka, ācārya Mahidāsa, citing an ancient verse, pointed at the status of Āśvalāyana as the progenitor of a branch–
ṛcām samūha ṛgvedastamabhyasya prayatnataḥ
paṭhitaḥ śākalenādau caturbhistadanantaram.
śānkhyāśvalāyanau caiva māṇḍuko vāskalāstathā
vahavṛcāṃ ṛṣayaḥ sarve pañcaite hyekavedinaḥ.
According to the branch-division of of this Āśvalāyana branch of Veda, it should have its own Mantrasaṃhitā, Brāhmaṇa-text, Śrautasūtra, Dharmasūtra, Gṛhyasūtra etc. But we have only the Śrautasūtra and Gṛhyasūtra of Āśvalāyana. In Praśna Upaniṣad (1.1;3.1), we have the mention of Āśvalāyana. In Kaivalya Upaniṣad (1.1), it is found that God Śiva describes his own glory to Āśvalāyana.