Trisong Detsen
In the 8th century, King Trisong Detsen (755-797 CE) established it as the official religion of the state, and commanded his army to wear robes and study Buddhism. Trisong Detsen invited Indian Buddhist scholars to his court, including Padmasambhāva (8th century CE) and Śāntarakṣita (725–788), which are considered the founders of Nyingma ("The Ancient Ones)", the oldest tradition of Tibetan Buddhism.