In order to select his spiritual successor, Guru Nanak had set a series of tests to reveal that one exceptional Sikh who could unflinchingly maintain his composure, devotion, and state of humility. Baba Buddha (1506-1631) was one of the earliest disciples of Guru Nanak, having served the Guru diligently all his life. Baba Buddha had failed the Guru and was deeply disturbed by feelings of unworthiness as a Sikh; his anguish did not escape the Guru's notice. In the tradition of the Akali Nihangs, a Sikh attains the ultimate honour by serving the Guru - the greater the service, the greater the honour. To redeem his loyal Sikh, Guru Nanak set Baba Buddha a vitally important task. He blessed 'Bhai' (brother) Buddha with the gift of Sanatan Shastar Vidiya; he was requested to guard this science until circumstances necessitated its return to the Guru once more.
It was the fifth Sikh Guru, Arjan Dev (1563-1606) who, while sensing troubled times ahead began the process of militarising the Sikhs. He requested the Jat warrior Baba Buddha (over 90 years old at the time), to tutor his only son, Hargobind (1590–1644) in Sanatan Shastar Vidiya. As Guru Nanak's prediction of troubled times was unfolding, Baba Buddha was to fulfil his pledge. He taught the young Hargobind the combat arts as passed down to him by Guru Nanak:
"The boy was an apt pupil; always grateful to his teacher and awarding him due reverence. He enjoyed gaining the priceless knowledge."
(Gurbilas Patshahi 6 (1720), eds. Joginder Singh & Dr Amarjit Singh, Punjab: Bhasha Vibhag (1998), 54-55)
Other young men were also taught Sanatan Shastar Vidiya. Guru Arjan Dev also employed his trained Rajput, Jat etc. warriors to assist Baba Buddha. Warriors such as Bhai Kalyan Sud, Bhai Bidhi Chand, Bhai Aditi Soini, Bhai Partapu, Bhai Ganga Sehgal, Bhai Sigaru, Bhai Jetha, Bhai Piraga, and Bhai Bhanu were the nucleus in building the army of the Guru. He declared:
"We are to take up arms in the form of Guru Hargobind. We are to take them up. The time of Kalyuga is to pervade (i.e., dangerous times are coming). In practicing the science of weapons Shastar Vidiya we are to snatch the 'Mirs' (chiefs) 'Miri' (chieftainship). In understanding the love of 'Shabad' (sacred teachings)we will take 'Piri' (spiritual authority). You remain in the presence of the sixth king. One eats the salt of the kings (i.e., pledges himself to a king) and surrenders his body to them. You will attain [here] alongside spiritual salvation the manner of correct living of one who has attained salvation whilst alive."
(Sikhan di Bhagat Mala, ed. Trilochan Singh Bedi, (Publication Bureau Punjabi University, Patiala, 1994),126)
Guru Hargobind would go on to establish the original fighting school of the Sikhs - the 'Ranjit Akhara' (the invincible martial arts school); a direct descendent of the original Shiv Akhara. The Ranjit Akhara would be based at the 'Akal Takht' (the throne of the immortal one) based at Amritsar with its army, the 'Akal Sena' (army of the immortals). From this original Akhara, as warriors attained Sanatan Shastar Vidiya; accomplished students would go on to establish new Akharas in their own names. One such Akhara that exists today is the Akali Nihang Baba Darbara Singh Sanatan Suraj Bansia Shastar Vidiya Shiv Akhara (established in 1661), which is at present headed by Gurdev Nidar Singh Nihang.
During the 17th century, a warrior named Bidhi Chand was taught Shastar Vidiya directly from the sixth Sikh Guru. He in turn instructed Guru Hargobind's eldest son Baba Gurditta who would impart the knowledge to his youngest brother, the future ninth Guru of the Sikhs, Tegh Bahadur (1621–1675). Guru Tegh Bahadur would later take under his wing a 'Khatri' (administrative / military caste) Sikh named Darbara Singh (1645-1735) after whom the present day Akhara is named.