The definition of Early Buddhism and EBTs is not entirely the same as Ven. Yinshun:
All extant EBTs are sectarian. However, their essential form (structure) and content, recognised in common by all schools of Sectarian Buddhism, were certainly established in the period of Early Buddhism.
Early Buddhism contains both the first and second councils (before the first schism of the Sangha into two main branches, Mahasanghika and Sthavira).
The Sutra (teachings) collections of Early Buddhism include SA/SN (originated at the first council) and MA/MN, DA/DN, and EA/AN (originated at the second council, one hundred years after the death of the Buddha).
SA/SN represents the situation with regard to the compilation of the Buddhist teachings shortly after the death of the Buddha.
MA/MN, DA/DN, and EA/AN represent the Buddhism of the period just before that second council.
For the studies in Early Buddhism/EBTs, it will be better to see clearly and respect the differences and similarities between the divergent, non-identical texts and traditions, particularly between SA/SN and other versions of literature in Buddhist history.
The SA/SN collection itself also contains three different classifications/angas. Ven. Yinshun sees the gradual formation of SA/SN as corresponding to the three angas formed in sequence (the sutra-anga portion was the earliest of the three).
According to Ven. Yinshun, SA/SN was not at first being termed as nikāya or āgama ‘collection’, but generally named the ‘Connected Discourses’ 相應教 Saṃyukta-kathā . About the term Saṃyukta-kathā, see p. 899, note 21 in the paper 2020 by Choong Mun-keat.
Calling the Saṃyukta/Saṃyutta as āgama/nikāya ‘collection’ was until when the other three nikāyas/āgamas (MN/MA, DN/DA, AN/EA) were gradually developed and expanded from it (相應教 Saṃyukta-kathā). Cf. pp. 10-11 in Choong Mun-keat’s Fundamental Teachings of Early Buddhism (2000). Ven. Yinshun: Samyutta/Samyukta Buddhism
(pp. 3-6, 10-11 in Choong Mun-keat’s Fundamental Teachings of Early Buddhism)
Pages 2-7 from The Fundamental Teachings of Early Buddhism Choong Mun-keat 2000.pdf (440.2 KB)
Pages 7-11 from The Fundamental Teachings of Early Buddhism Choong Mun-keat 2000.pdf (605.1 KB)