I just read "Asia, Africa, and the History of Philosophy" which details how before Meiners, Kant, and Hegel the idea that Greece was influenced heavily by philosophy from India, China and Egypt (amongst others but those are the most prominent) was uncontroversial, most histories of philosophy would acknowledge that Greece wasn't the first, even if they didn't have the knowledge of language required to go into detail about the philosophers not from Europe. It was under the influence of those three Germans that the current philosophical canon became solidified as either Philosophy starting in Greece or that Greece was so exceptional that they took the meagre offerings of the other cultures and turned it into something grand, so we can just ignore the others.

Particularly things like a lot of Plato's ideas to do with the world of forms and the like, was kind of alien to Greek culture but is found in the vast majority of Indian texts before him (or a similar idea).

Unfortunately (for you) the book is mainly concerned with the history of the historiography of philosophy, and not particularly concerned with defending and detailing the influences so there isn't a lot of detail on that end. But I would recommend reading it, it's relatively small so you can knock it over in a couple days.