What is "atisa"

(; ; ) (982 - 1054 CE) was a Buddhist Bengali religious leader and master. He was one of the major figures in the spread of 11th-century Mahayana and Vajrayana Buddhism in Asia and inspired Buddhist thought from Tibet to Sumatra. He is recognised as one of the greatest figures of classical Buddhism, and Atisa's chief disciple Dromtön was the founder of the Kadam School. Atisa is also considered to be a key figure in the establishment of the Sarma schools of Tibetan Buddhism.