Yogācāra was associated with Indian Mahayana Buddhism in about the fourth century. Asaṅga and Vasubandhu are considered the classic philosophers and systematizers of this school.
The origin of the Yagacara doctrine can be found in SA (Saṃyukta-āgama), which is connected with the earliest Buddhism.
The sūtra-mātṛkā (sūtra matrix, 契經, 摩呾理迦 or 本母), essentially a commentary on a portion of SA, found in the Vastusaṅgrahaṇī of the Yogācārabhūmi, follows the sequence of SA.
This discovery confirms that the Sarvāstivāda tradition regarding SA is attested to in the Yogācārabhūmi.
The sūtra-mātṛkā contains these seven topics:
Discourses Connected with the Aggregates
Discourses Connected with the Sense Spheres
Discourses Connected with Causal Condition
Discourses Connected with the Nutriments
Discourses Connected with the Truths
Discourses Connected with the Elements
Discourses Connected with the Path: the Stations of Mindfulness, etc., of the Enlightenment Factors.
These seven topics are considered by Ven. Yinshun to be the most fundamental and earliest portion of the ‘Connected Discourses’ (相應教, saṃyukta-kathā) of SA.
They are found in the five major sections (varga) on aggregates, sense spheres, causal condition (including nutriments, truths and the elements) and path of the extant SA/SN.
These sections of the ‘Connected Discourses’ are identified by Ven. Yinshun as the sūtra-aṅga portion of SA/SN
See pp. 898-9 in Choong Mun-keat, 2020 “Ācāriya Buddhaghosa and Master Yinshun 印順 on the Three-aṅga Structure of Early Buddhist Texts” .
It’s worth noting that Vasubandhu himself noted that the key doctrine of the ālayavijnana was the same as what the Theravadins call bhavaṅgacitta, or the Mahasanghikas, the mūlacitta. (Source, unreliable memory, please correct me!)
I’m no expert, but I believe this is wrongly translated; or so has been argued by Kalupahana. The Sanskrit is vijñaptimātra, where vijñapti is a causative form, and hence functionally identical to the Pali manomaya “made by mind”, while -mātra does not mean “only”, but “mere”.
A better translation would be “mere expressions of consciousness” or “mere products of consciousness”. Vasubandhu was pointing to the way our experience of the world is formed by our intentions and perceptions. He wasn’t advocating an ontological idealism. Translators are overly-influenced by later schools that were indeed idealist.