A number of monasteries grew up during the Pāla period in ancient India in the eastern regions of the Indian subcontinent, comprising Bengal and Magadha. According to Tibetan sources, five great Mahaviharas stood out: Vikramashila, the premier university of the era; Nalanda, past its prime but still illustrious; Somapura Mahavihara; Odantapurā; and Jaggadala.[2] The monasteries formed a network; "all of them were under state supervision" and there existed "a system of co-ordination among them ... it seems from the evidence that the different seats of Buddhist learning that functioned in eastern India under the Pāla were regarded together as forming a network, an interlinked group of institutions," and it was common for great scholars to move easily from position to position among them.[3] Xuanzang of China was a noted scholar who resided at the Somapura Mahavihara (the largest monastery in ancient India), and Atisa traveled from Bengal to Tibet to preach Buddhism.