Most of the Indian Air Force MiG-21s were license built by Hindustan Aeronautics, the major aerospace company in India.
Production of both MiG-15s and MiG-21s was eventually farmed out by the Soviet Union to satelite states in the Warsaw Pact to make room for the more modern MiG variants on Soviet assembly lines.
A good number of 15s and 21s came off of Polish,Czech and Indian assembly lines on proper licenses, far more came off of Chinese lines with sometimes no license at all.
I'm not certain to what standard Hindustan Aeronautics built the Indian 21s, from what I understand, they started building them from Soviet supplied kits, but then eventually were able to get permission to machine their own components from scratch to build more.
The rule with the 21 is to remember that it was the most produced and widely used jet fighter in history. it was produced in many nations in many variants and to this day its final production numbers are a point of intense argument. There's a lot of grey area to cut through to get to the truths about where the aircraft you saw has been in its career:
Did India get it new or second hand?
If they got it second hand, who had it before them?
Did it serve in any war zones?
Lots of questions.
On the other hand, India doesn't have the best economy in the world and perhaps the aircraft you were looking at suffered the unfortunate effects of the baling wire and duct tape field repair kit a few too many times.