I'd really like to learn more about the culture, societies, history of this Greco-Buddhist era. Based the associated wiki it looks like I'm kind of fishing for books that might talk about Alexander the Great, the Indo-Greek Kingdom, and/or Kushan Empire. I'd also be really interested to read about longer term impacts on both sides from these interactions.
A good start would be The Archaeology of the Hellenistic Far East: A Survey by Rachel Mairs. While it's not an introductory text in itself, being basically a review of the current literature, it's a solid roundup of a lot of the archaeological and papyrus sources. It should be able to point you in the direction you want. Be warned, a sizeable chunk of the bibliography leads to sources in French or Russian.
It also discusses some of the problems with the traditional narrative histories used as starting points and the legacy on colonialism in the field.
There's a PDF accessible from Mairs' own site here. It was published in 2011 and there's a few updates around the site of more recent works.
Did any remnants of the Greek religion and culture remain in the practices of the region after the waning of the Greco-Bhuddist kingdom(s)?