This is a compilation of forty-nine heterogeneous sūtras, present in both the Kangyur and the Chinese Tripiṭaka.
The Heap of Jewels—like the other distinct collection preceding it in the Kangyur, the Ornaments of the Buddhas (Buddhāvataṃsaka)—is often described as a sūtra, its full Sanskrit title being Mahāratnakūṭasūtra (“The Sūtra of the Great Heap of Jewels”), and in Tibetan ’phags pa dkon mchog brtsegs pa chen po’i chos kyi rnam grangs le’u stong phrag brgya pa (“The Noble Dharma Discourse of the Great Heap of Precious Jewels with a Hundred Thousand Chapters”). Unlike the Ornaments of the Buddhas, however, its component texts or chapters are explicitly presented as independent works. Many of them are individually cited in the treatises of the great Indian masters and are known to have circulated as sūtras in their own right; only five are still extant in Sanskrit.
Although the name Ratnakūṭa (“heap of jewels” or, more exactly, “piled-up jewels”) seems quite appropriate for such a compilation of precious scriptural works, it is in fact the name by which just one of the texts in the collection, the Kāśyapaparivarta (The Discourse for Kāśyapa, Toh 87) was originally known, and seems to have been applied to the whole collection only later. Citations from a Ratnakūṭasūtra in works by Asaṅga, Śāntideva, and other authors all refer to the Kāśyapaparivarta, which is sometimes therefore designated the “old” Ratnakūṭa.
The history of the Heap of Jewels remains unclear. Tibetan historical tradition, as mentioned briefly in the Degé Kangyur catalog and recounted more fully by Tāranātha, tells us that the originally much larger collection (with a thousand chapters, or even the hundred thousand of the full title) was reduced to its current forty-nine texts by an arson attack on the library at Nālandā. The date of this event, said to have been responsible for the decimation of many other scriptures, too (including the Buddhāvataṃsaka), is placed sometime before the lives of Asaṅga and Vasubandhu, along with accounts of other calamitous episodes during a period of political turbulence and unstable patronage for Buddhist institutions in India.
According to modern historical methods, while the Heap of Jewels’ component texts can be traced back in some cases to dates early in the appearance of Mahāyāna texts, evidence that the collection as a whole existed in India (i.e., before it appeared in China) is present but sparse. The earliest mention of it is in the Daśabhūmikavibhāṣa, attributed to Nāgārjuna and translated into Chinese by Kumārajīva in the early fifth century. The sixth-century Gandhāran translator Jñānagupta seems to have spoken of it, and the famous Chinese traveler Xuanzang was asked to translate it in 664, although he only made a start. It was Bodhiruci who collected and translated it into Chinese in the first decade of the eighth century, using twenty-three texts already circulating in Chinese and adding twenty-six new translations of his own; it is reasonable to assume that he was using an Indian (or perhaps central Asian) prototype. The Tibetan collection follows the Chinese closely in structure and composition, but most of the texts were evidently translated directly from Sanskrit originals (with a few exceptions, namely The Teaching of the Armor Array, The Teaching to Venerable Nanda on Dwelling in the Womb, The Teaching to Venerable Nanda on Entry into the Womb, and The Questions of the Girl Vimalaśraddhā—Toh 51, 57, 58, and 84, respectively—which are known to have been translated from the Chinese). The Tibetan translation is mentioned with a full list of its present component texts in the early ninth-century Denkarma catalog, though surprisingly the other early inventory, the Pangthangma (which is thought to be of a slightly later date) lists only nine works under that heading (the other forty being listed in more general size-ranked categories), and the Mahāvyutpatti names some of the Ratnakūṭa sūtras without any mention of the collection’s name.
The sūtras in the collection cover a wide range of subjects and have diverse origins. Two (The Teaching to Venerable Nanda on Dwelling in the Womb, Toh 57, and The Teaching to Venerable Nanda on Entry into the Womb, Toh 58) are Śrāvakayāna works from the Mūlasarvāstivāda Vinaya; one (The Perfection of Wisdom in Seven Hundred Lines, Toh 90) is a Prajñāpāramitā sūtra; and two (The Array of Amitābha, Toh 49, and The Array of the Tathāgata Akṣobhya, Toh 50) are Pure Land works. The majority are Mahāyāna sūtras dealing with classic themes such as emptiness, compassion, wisdom, and the bodhisattva’s vows and path. The very variety of its works suggests that it may have been deliberately compiled as an anthology representing many topics.
Jonathan Silk (1994) has argued in his study of the Ratnarāśisūtra (The Mass of Jewels, Toh 88), a text in the collection with affinities to the Kāśyapaparivarta, that the shared features of these two texts point toward the characteristics of a specific kind of “textual community,” perhaps one of many such textual communities influential in the rise of the Great Vehicle. Three of the defining features of this proposed textual community that can be gleaned from the work of Silk and others (Nattier 2003, Boucher 2008) are an absence of discernible antagonism between śrāvaka (hearer) and bodhisattva practitioners; an emphasis on monastic ideals; and a concomitant valorization of renunciation and the ascetic life. While helpful as a starting point, this hypothesis does not seem to be supported fully by all the texts in the collection, however, and the possible basis upon which the collection was compiled remains to be explored.