It has been documented how much syncretism occurred between the Hellenistic Greeks and Sramanic culture during Alexander the Great's eastern campaigns in Bactria, India, etc. and how philosophers such as Pyrrhon the Skeptic who accompanied him brought back many elements of the culture which influenced later Hellenistic philosophy such as Skepticism, Stoicism and Epicureanism
My question, however, is how much exposure Alexander's teacher Aristotle would have had to Eastern philosophies such as Buddhism, Taoism, etc. as there are no doubt many comparisons to be made (e.g. Aristotle's 'Golden Mean' vs. the Buddha's 'Middle Way', just scratching the surface)
Are these overlaps simply coincidence, or did some of Aristotle's teachings (which helped shape Western culture and religion) come directly from Eastern influence?
My background is in philosophy, and specifically ancient greek and eastern philosophy, with a smattering of 19th century German philosophy.
No doubt there was some communication and there are a lot of synchonicities in the Greek philosophy and Buddhist philosophy, it's very hard to say. Many argue that Diogenes is a very Buddhist / Zen character, and was a contemporary of Alexander and Aristotle, but the record suggests he was that way before he met Alexander, at least. You gave some very concrete examples, like Pyrrhon.
But in a direct sense there's really no proof. Perhaps he discussed ideas with people during their wine drinking sessions that had heard about eastern thought or a version of it via philosophers who were already establish in greece and heard new ideas (like skepticism) and liked a few concepts or disagreed with them and formed his own in response, but he never mentioned anything eastern philosophy explicitly in his corpus.
In western philosophy and with major, canonical philosophers, it's really not until Schopenheaur and then Nietzsche that eastern philosophy is seriously discussed by name along with western ideas. It became kind of a popular thing in 19th century german academic circles. Even today, eastern and western philosophers who are looking to bridge that gap usually start with the work done there by those two and others, because they laid the groundwork for serious discussions of bridging the two ideas. Of course, that's with 2000+ years of further religious, cultural, linguistic and philosophic changes on every side.
It's more of a coincidence (turns out a lot of philosophers asking the same questions end up with similar answers, even in roundabout ways, around the world) than anything that, in a historical sense, there is a record of.
On the flip side, there was similar influence to eastern thought due to interactions with the greeks, but I can't provide any source for that, I know a lot less about it.
A more major interaction that's usually under appreciated is all the influence Aristotle had on arabic thought. If it wasn't for them holding on to the texts and continuing to study them during the late middle ages, we literally would have lost all copies of the extent text forever