The Four Kumaras namely: Sanaka, Sanandana, Sanatana, and Sanat Kumara are traditionally the four mind-born sons of Lord Brahma. Famous throughout the Puranic literature, they are found also in the Upanishads. They are renowned yogis, who requested their father for the boon of remaining perpetually five years old. They were created by their father in order to advance creation, however, they chose to undertake lifelong vows of celibacy (brahmacharya). After obtaining initiation into the Shri Gopala Mantra, these four brothers then left meditations into an impersonal God, and realised the truth lies beyond the impersonal, in the Highest Person, the Supreme Lord Shri Krishna. Having obtained His grace and being initiated into Vaishnava tradition, they began to spread the teachings of the path of renounciation. During initiation into this Vaishnava tradition, they received the Shri Shaligrama Shila known as Shri Sarve Svara Bhagavan, which has been passed on from each Guru to disciple since their time. The Supreme Lord Shri Krishna, in His conversation with Uddhava in the 11th Canto of the Bhagavata Purana declares: etavan yoga adisto macchisyaih sanakadibhih – 'I taught this yoga to My disciples, the four brothers headed by Sanaka'.
During initiation, the most holy 18-syllabled Shri Gopala Mantra was given to them, a fact recorded in the Vishnu Yamala:
The holy eighteen-syllabled mantra comes from the lotus-like mouth of Lord Shri Krishna (Shriman Narayana). It was accepted by the Four Kumaras and also by their disciple, Shri Narada Muni.
This mantra is the Vaidika mantra from the Gopalatapinyupanishad of the Atharva Veda. This is the initiatory mantra still used in the Sampradaya today. Shri Sanat Kumara Samhita is a famous treatise on the worship of Shri Radha Krishna authored by the brothers, and they have also produced the Shri Sanat Kumara Tantra, part of Pancharatra literature. Their teachings can be found throughout all Vedic literature. It is due to the tradition coming into contact with the Four Kumaras that it came to be known as the Sanakadi Sampradaya or the Kumara Sampradaya.