Sumathi

Namaste Amanbeer ! 

The historical antiquity of yoga if seen academically goes back to pre-history where on the  cave walls we can find such descriptions . So Historically to put it straightfoward , it's presence can be seen from the Harappan civilization ( one of the oldest one parallel to mesopotamian ) . We find seals of Yogi stiing in meditative postures , banyan trees , animal motifs etc which gives substantiates yoga practises presence during that time . Now every day new researches are also coming up with emergence of new  scientific methods of archeology . And this is again to refer and refer on constant basis . 

Om 

Sumathi 

Yoga counsellor / Yoga Therapist / wellness coach 

Namaste Riddhi 

Now let's understand it in this way . We first take definition of yoga with the refference of Maharishi "Patanjali " who in his aphorism " Yoga Darshan " describes yoga as " calming the impressions of mind" . Now to bring that state there are various stages of practises . For a beginner it starts with "Bahiranga Yoga " that is the external yoga where we work mostly body -breath centric . Here we can put HATHA YOGA as balancing and preparing mind - body complex . Under hatha yoga many modern schools developed like the contemporary classical hatha yoga , ashtanga , vinyasa , yin etc . Afterwards comes the intermediate journey and hence comes the Raj yoga that also comes under 'antarang yoga ' or internal yoga where a sadhak has mastered ones external equipments and now can work on the internal that is senses and mind . From the mastery here the ultimate path of kriya yoga yoga starts . So it all is a gradua path depending upon the personality , previous samskaras , prarabdhas and also the interest of a sadhak / Yogi 

I hope this answer provided you some useful background for your query 

Om 

Sumathi 

Yoga counsellor / Healer / wellness expert