Dalrymple stated aim in this book is to revive an understanding of how significant India has been as a global power, especially east towards Arabia, North Africa and Europe, and west towards South-East Asia. This is largely achieved through his coverage of the development and spread of Buddhism and Hinduism, with a bit of Sanskrit, and the significance of numeral notation.
The book is interesting, but perhaps because I didn't come in unconvinced, I wasn't entirely sold on the structure. I found myself wanting to read more specific books on those specific things - especially the religions, where the rapid cultural conversion is fascinating, but I'm not sure coming out I entirely understand why.
I have come out with a new list of places I really, really want to visit though, so that was totally worth it.