The Nyingma school of Tibetan Buddhism

 The Nyingma school of Tibetan Buddhism has the longest established history of the transmission of all of the four major traditions of Tibetan Buddhism. This is reflected in the name Nyingma which literally means “Old Order” The other three main schools of Tibetan Buddhism including Sakya, Kagyu, and Gelug are collectively referred to as Sarma “New Order” Because they rely on the Tibetan translations of Indian Buddhist texts that were prepared under the system established during the period of the second dissemination of Buddhism into Tibet.

https://tibetuniversaltravel.com/nyingma/