There is a good book by Romila Thapar, “Early History of India” , for the general overview of early history. You probably want her latest edition, they changed a lot over the years.

A bit more classical but thorough is a History of India by Herman Kulke and Dietmar Rothermund.

And the best one to go into detail is “The Rigveda : a guide” by Joel P Brereton & Stephanie W Jameson.