Wandering asceticism (shramanism) was the counterculture way of the yogi rather than the career of the brahmin, the establishment temple priest (Brahmanism).
Setting off from the palace, he chose the path of the wandering recluse under one renowned yogi, Alara Kalama, then another, Uddaka Ramaputra.
Siddhartha began his spiritual career in his final birth by approaching a prominent teacher (guru), a great yogi of the time, asking to be a disciple (chela).
meditation, which the Bodhisatta engaged in at length.
But austerities, or tapas, is also a yogic practice. Breath-control (restraint), or pranayama, as well as other restraints (yamas) -- all of these and more were part of his practice, although they were only systematized five or six centuries later by the Sage Patanjali as an eight-limbed path (ashtanga).
Integral Yoga is the eightfold "union" of factors that unites a person, optimizing all that is necessary to gain samadhi (the first four meditative absorptions, jhanas, intensified-concentration), which forms the foundation for insight-practice (vipassana).
And it is the culmination of these two Path-factors that leads to enlightenment.