One of the most important figures of 10th-11th century of Vajrayāna was the undoubtedly the monk Atiśa (Jo-bo rje dPal-ldan A-ti-sha) (982-1054).
Few in medieval India possesed the monastic discipline, knowledge, and realizational depth of Atiśa.
Atisha was born as prince Chandragarbha, the son of "King Kalyana the Good" in Bangala, Jahor in the present day Bangaladesh. At an early age he dedicated himself to the Dharma and spared no effort to seek out and study under the most accomplished masters of his time. These efforts led him to his root teacher Serlingpa who lived in Sumatra (or Java) Indonesia where he recieved a unique boddhicitta transmission from his root Guru Serlingpa.
Upon retuning from Indonesia he served as Vinaya master of the Buddhist University of Vikramaśila and was revered by all.
Receiving an invitation from the Tibetan King Yeshe wo (Ye-shes 'od) he traveled to Tibet, transmitting his immense wisdom. Atisha spent seventeen years in Tibet: three years in Ngari, nine years in Nyetang near Lhasa, and five years in various other places until his death at the age of seventy-two He was suceeded by his lay disciple Dromtonpa ('Bron-ston rGyal-ba'i 'byung-gnas) (1004 - 1064) who established the Radreng Monastery which became the most important center of the Kadam (bKa'-gdams) tradition.