Upaniṣadic Idealism

Er [i.e. der Buddhismus] wandte sich aber nicht nur gegen den Materialismus, sondern auch insofern gegen den Upaniṣadidealismus, als er bestritt, daß es ein ewiges brahman oder eine ewige Seele gebe; er verfocht demgegenüber den Gedanken eines ständigen Werdens in allen natürlichen und geistigen Erscheinungen. Das war eine großartige, wenn auch naive Dialektik (Frauwallner 1956: xii).

But this is not found in the revised edition. 

Udālaka’s Hylozoism

Udālaka’s Hylozoism (i.e. “the doctrine that nature is imbued by life even in the apparently inert and lifeless”) is said to be the first form of (Indian) Materialism. See Frauwallner 1956: xi.

Jaina Atomism

“Neben dem Buddhismus entwickelten Ideologen der handeltreibenden Schicht den Jinismus als Religion mit einer eigenen Philosophie (Atomismus)” (Frauwallner 1956: xii).

Nyāya Realism

Bimal Matilal seems to be the first modern scholar to employ the term “Nyāya Realism,” and to introduce, discuss, and try to defend it. He obviously employs this term instead of or in favour of “Naive Realism” or “Direct Realism.” He juxtaposes Nyāya Realism to what he calls “Buddhist Phenomenalism and idealism” or “Buddhist phenomenalistic idealism” (favoured by Dharmakīrti). See Matilal 1986: 1–18 (introduction).

Sautrāntika Atomism

“Both Diṅnāga and Dharmakīrti seem to accept here the Sautrāntika atomism along its theory of external realities but this may be only a tentative concession” (Matilal 1986: 366). “Buddhist atomism reduces the spatial extension of external realities to atoms, the infinitesimals” (Matilal 1986: 367). Some Tibetan sources distinguish three conventions accepted by Diṅnāga and Dharmakīrti: (a) one non-analytical world-conforming convention, and two analytical-śāstric conventions, namely, (b) Sautrāntika’s convention which conforms the conventional mode of appearance (tha snyad snang tshul), and (c) Yogācāra’s convention which conforms the conventional mode of existence (tha snyad gnas tshul). Accordingly, Diṅnāga and Dharmakīrti, following conventional mode of appearance would accept Sautrāntika atomism, but Yogācāra idealism from the perspective of the conventional mode of existence. To be noted is that most phenomena considered to be substantially existent by the Vaibhāṣika school are said to be considered to be non-substantial (i.e. only nominally existent) by the Sautrāntika school. See, for example, dKon mchog ’grel (pp. 44.23–45.2).

Tsong-kha-pa’s Realism

Tsong-kha-pa’s Realism:

Dreyfus 1997: 454.