We have only recently begun to recognise the work produced by Madhava who lived in Kerala, South India. Much research remains to be done and many clues are lost to us now. We only have some of his astronomical accounts left to us - all of his mathematical work has been lost.
What we do know of Madhava is learnt through the work of later mathematicians Nilakantha and Jyesthadeva who based their work on Madhava’s. There is some debate as to whether the work attributed to these two is in fact the work of Madhava, but most recognise it as later work.
Texts published by his followers show us that Madhava discovered what is now known as Maclaurin’s series - the expansions of sin x, cos x, and arctan x which were discovered by Madhava years earlier in around 1400.