the Panjab or Hindustan, where their progress was hindered at first by a healthy and vigorous Hinduism and subsequently by Mohammedan invasions.  But from 700 to 1197 A.D.  Bengal was remote alike from the main currents of Indian religion and from foreign raids:  little Aryan thought or learning leavened the local superstitions which were infecting and stifling decadent Buddhism.  Hsuean Chuang informs us that Bhaskaravarma king of Kamarupa[320] attended the fetes celebrated by Harsha in 644 A.D. and inscriptions found at Tezpur indicate that kings with Hindu names reigned in Assam about 800 A.D.  This is agreeable to the supposition that an amalgamation of Sivaism and aboriginal religion may have been in formation about 700 A.D. and have influenced Buddhism.

In Bihar from the eighth century onwards the influence of Tantrism was powerful and disastrous.  The best information about this epoch is still to be found in Taranatha, in spite of his defects.

He makes the interesting statement that in the reign of Gopala who was a Buddhist, although his ministers were not (730-740 A.D.), the Buddhists wished their religious buildings to be kept separate from Hindu temples but that, in spite of protests, life-sized images of Hindu deities were erected in them.[321] The ritual too was affected, for we hear several times of burnt offerings[322] and how Bodhibhadra, one of the later professors of Vikramasila, was learned in the mystic lore of both Buddhists and Brahmans.  Nalanda and the other viharas continued to be seats of learning and not merely monasteries, and for some time there was a regular succession of teachers.  Taranatha gives us to understand that there were many students and authors but that sorcery occupied an increasingly important position.  Of most teachers we are told that they saw some deity, such as Avalokita or Tara.  The deity was summoned by the rites already described[323] and the object of the performer was to obtain magical powers or siddhi.  The successful sorcerer was known as siddha, and we hear of 84 mahasiddhas, still celebrated in Tibet, who extend from Rahulabhadra Nagarjuna to the thirteenth century.  Many of them bear names which appear not to be Indian.

The topics treated of in the Tantras are divided into Kriya (ritual), Carya (apparently corresponding to Vinaya), Yoga, and Anuttara-yoga.  Sometimes the first three are contrasted with the fourth and sometimes the first two are described as lower, the third and fourth as higher.  But the Anuttara-yoga is always considered the highest and most mysterious.[324] Taranatha says[325] that the Tantras began to appear simultaneously with the Mahayana sutras but adds that the Anuttara-yoga tantras appeared gradually.[326] He also observes that the Acarya Ananda-garbha[327] did much to spread them in Magadha.  It is not until a late period of the Pala dynasty that he mentions the Kalacakra which is the most extravagant form of Buddhist Tantrism.