During the Gupta period (4th–6th centuries) and the empire of Harṣavardana (c. 590–647 CE), Buddhism continued to be influential in India, and large Buddhist learning institutions such as Nalanda and Valabahi Universities were at their peak. Buddhism also flourished under the support of the Pāla Empire (8th–12th centuries). Under the Guptas and Palas, Tantric Buddhism or Vajrayana developed and rose to prominence. It promoted new practices such as the use of mantras, dharanis, mudras, mandalas and the visualization of deities and Buddhas and developed a new class of literature, the Buddhist Tantras. This new esoteric form of Buddhism can be traced back to groups of wandering yogi magicians called mahasiddhas.