Sourced: https://isha.sadhguru.org/en/wisdom/article/classical-yoga-an-introduction-to-the-origin-of-yoga

Over 15,000 years ago, in the upper regions of the Himalayas, a yogi appeared. Nobody knew where he came from or what his origins were. He just came and sat still – absolutely still. People gathered in huge numbers because his presence was quite extraordinary. They waited, hoping for a miracle, but he was completely oblivious of them. For months on end, there was no sign of life, they couldn’t even see if he was breathing or not. The only signs of life were the tears of ecstasy that flowed out of his eyes on occasion.

Slowly, people began to drift away. The miracle they were waiting for did not happen; they couldn’t see that a person sitting unmoving was a great miracle in itself. He was obviously beyond the physical, but people missed that. Everyone left, except for seven hardcore beings who hung on. These seven people followed the yogi wherever he went. When his attention fell upon them, they pleaded with him, they wanted to experience whatever was happening to him. He dismissed them. “This is not for people who are seeking entertainment. This takes something else. Go away.” But they hung on. Looking at their perseverance, he said, “Okay, I’ll give you a preparatory step. Do this for some time. After that we’ll see.” The seven men began to prepare. Days rolled into weeks, weeks into months, months into years, but the yogi’s attention did not fall upon them again.

84 years of hard sadhana had passed by, and one day, the yogi once again took notice of the seven men. He saw that for 84 years these people had been preparing themselves. They had become shining receptacles, he could not ignore them anymore. He watched them keenly, amazed that these people had become so wonderfully receptive. On the very next Full Moon day, the yogi turned south and sat as a guru to these seven men.  Because we did not know his name, we did not know who he was, we call him Adiyogi – the first yogi. That full moon day is still observed today as Guru Purnima.

Guru Purnima is a significant day in the yogic tradition, because this was the first time Adiyogi opened up the possibility for a human being to evolve consciously. For the first time, the entire science of how a human being can evolve into his or her ultimate possibility was taught to these seven men, the celebrated Saptarishis or Seven Sages. Adiyogi put seven different aspects of yoga into these seven different people. This became the foundation for the seven basic forms of yoga. Even today, yoga has maintained these seven distinct forms.

Adiyogi expounded these mechanics of life to the Saptarishis for many years. When all of the seven disciples had fully attained, he told them, “Go out into the world and spread this.” Legend has it that he sent one to Central Asia, one to South America, another to North Africa and the Middle East, another to South East Asia, another came down to the lower parts of the Himalayas, which is now considered as the Indian Himalayas, one stayed with him, and the last one came to the southern part of India. This was Agastya Muni, and he ensured that every human habitation south of the Deccan had a spiritual process – not as a teaching, a philosophy, or a religion – but as a way of living. Even today, his work is still visible in the culture around here. For this part of the world, the only goal has always been liberation.