Yoga is mentioned in Rig Veda. Ashtang yoga is from Sage Patanjali and is believed to be most effective.
Basically yoga means mind, body and soul harmonious union. Postures are just one part of yoga and there is much more then that.
In fact if we are not working on our own selves and are just doing postures then we are missing huge part of yoga.
Yoga is diving deep into our ownselves and resolving all the knots.
It is feeling whole and complete in our own selves. It is diving deep and collecting our scattered energy from outside, going in deep rest and coming back in our full power.
There was lot of respect and gratitude for those who helped in connecting people to their most highest selves but no where people were encouraged to connect to any outside person, place or thing.
This outside connection thing started much later.
So, enjoy your mind, body and soul harmonious union today