Indian Air Force bought MIG-29 aircrafts in 1960s and found them perfectly fit for their needs and buy thousands(1000s) of MIG-29 just because of the ruggedness of the design and the ultra low per unit cost. 

This is a state every armed forces go through. The reason is very simple they once had a product that was so perfect for their needs that they just bought it in huge nos, now the product is ageing and it has to be retired but the huge no. in the past which was a blessing has now turned to a curse as you just cannot find the product that matches your previous perfection so being a large Engineering and Scientific nation with millions of dollars at your disposal you embark on creating your dream to replace your previous dream.

Now as you see it served the force well until the 80s but after that it started showing age now the aircraft was to be replaced and the problem is aircraft technology has improved by leaps and bounds and that improvement has come with a cost now you cannot just order 1200 aircrafts without cutting funds from vital programs of the nation and the aircrafts could not be retired too as it would make the force weak in shear no. In came the proposal to build this baby(Tejas)

but the problem was that you could not build a fighter jet from scratch in a day it took almost 20+ years to master the basic technologies and some of it is still being developed. In the meantime the force constantly upgraded the Mig but it has taken as much as it could take and in the early 2000s they started falling out of the skies attracting the infamous moniker of “Flying Coffin” for these legendary Jets. The force was forced to retire them and induct a relatively better but far behind it’s capabilities Tejas.

Now building on the years of effort the government sanctioned multiple other fighter programs to develop on one hand and to improve the Tejas on the other.

The government realized that India needs to get a stopgap arrangement until 2025–2028 before it’s own fighter programs bear fruit. Fortunately the force was flying MIG-29 Aircrafts from the 80s and India had recently upgraded it’s fleet to a much modern standard.