"There was a young bodhisattva, or messianic hero, Priyadarshana, who dwelt in the city of Vaishali in the Licchavi kingdom during the Buddha's time. He was a student of the great lay sage Vimalakirti, and he attained a high level of wisdom during Vimalakirti's famous session on nonduality, as recounted in the Holy Teaching of Vimalakirti Sutra. The Buddha subseqauently predicted that this young man would be reborn in South India four hundred years later and would be recognized by the word naga (dragon) in his name.
"Sure enough, a great master known as Nagarjuna emerged in South India in the irst century B.C.E., passing away at the ripe old age of six hundred plus in the fifth century C.E. (Western scholars date him in the second century C.E. and attribute Nagarjuna's deeds of other eras to other masters with the same name.) The legend goes that Nargarjuna was approached by nagas (dragons) in human form after one of his lectures at the monastery of Nalanda. They invited him to their undersea kingdom to see some texts they thought would be of great interest to him. He went with them magically under the sea and discovered a vast treasure trove of the Mahayana Sutras--not only the many versions of the Prajnaparamita but also the Inconceivable Liberation, the Jewel Heap, the Lotus, and the Pure Land Sutras. Nagarjuna spent fifty earth years studying these texts, and then he brought them back into human society and promulgated them throughout India
"... When he returned to India for the last time, he taught the Unexcelled Yoga Tantras ... founding the seminal "Noble" traditon of the practice of perfection stage yoga. His Tantric great adept persona is also essentially included in the semi-esoteric "direct mind transmission" tradition known as Ch'an and Zen in East Asia. Overall, Nargarjuna is associated with the angelic bodhisattva Manjushri, the archetype of transcendent wisdom, and is considered the pioneer of the wisdom teachings in the human realm."