There are multiple classical musical schools, the most prominent are the Hindustani (Indo-Persian) and Carnatic music. There is commonality in both with respect to notes and how combinations are formed to raag/raagas

Here is an example of Carnatic music for beginners (https://www.youtube.com/watch?v=_YNv1qwxJ0o)

I got hooked by listening to it, here's a piece that I've quite like https://www.youtube.com/watch?v=yfMHiTIm-zc