The Licchavis from the Indo-Gangetic plain migrated north and defeated the Kiratas, establishing the Licchavi dynasty. During this era, following the genocide of Shakyas in Lumbini by Virudhaka, the survivors migrated north and entered the forest monastery in Sankhu masquerading as Koliyas. From Sankhu, they migrated to Yambu and Yengal (Lanjagwal and Manjupattan) and established the first permanent Buddhist monasteries of Kathmandu. This created the basis of Newar Buddhism, which is the only surviving Sanskrit-based Buddhist tradition in the world. With their migration, Yambu was called Koligram and Yengal was called Dakshin Koligram during most of the Licchavi era.