In the late 900s and 1000s, people started new Buddhist and Bon traditions. Three of the four schools of Tibetan Buddhism were started during this time, as well as the first Bon monasteries. People who study Tibet's history call this time the Tibetan Renaissance. In 1042, the Indian Buddhist master Atisha came to Tibet. Atisha inspired a reform of Tibet's monasteries and wrote an important guidebook for people to gain enlightenment. These kinds of guidebooks are called lamrim, and all of the lamrim books in Tibet are based on Atisha's book. The largest school of Tibetan Buddhism, the Gelug school, was started by people inspired by Atisha, particularly the monk Tsongkhapa (1357-1419). Tsongkhapa's writings on philosophy became the new norm in Tibet. 