Earlier quoted context omitted.
Not only India, but Persia, countries in The Levant, North Africa and Mediterranean were highly developed before the advent of Islam (which originated amongst desert tribes). It is their knowledge which gave rise to the so called "Golden Age of Islam". Islamic conquest merely acted as a conduit for the spread of these ideas from one geographical region to another (a la the later Mongol Empire).
Central Asia certainly played its role too. I invite you to consider that when Jai Singh II built Jantar Mantar, he used "Islamic" sources (Zij) as well from there.
So any post Islamic Arab contributions to math would have to be stolen from India, using bloodshed - as if math is a treasure that can be lifted or looted or were existing amongst Arabs before Islam.