Strange then to find (~Greek) Gnostic writings that have the Pythagores and Zaratustra attending Babylonian seminars, with latter teaching the former 'astronomy'. Archaic, no doubt, but put yourself in the place of the reader (in the "West") at the time of the writing and ask youself: What "divide"? Political order differences? East Asia was and remains far more 'alien' to Iranians that Greeks. Note that the East Asians who do not have a dog in this fight, typically group us all together and don't make the distinction.

I don't think it's strange at all; dividing the world's people into two geographical groups doesn't imply the groups have no contact or interchange! It's well established historically, for example, that Egypt and Mesopotamia developed geometry long before the Greeks, and Pythagoras is said (by nominally historical accounts, intended to be more literaly factual than the Gnostic parables you're speaking of) to have studied in both places. Both Egypt and Mesopotamia were also part of the "East" for the Greeks until Hellenistic times, even though Cairo is geographically further west than Cyprus; maybe Cyprus was also "East"?

Also, to the Chinese, India was "the West". The famous novel Journey to the West is a fictionalized account of the Buddhist monk Xuanzang who traveled from China to India to bring back copies of Buddhist texts that had not yet reached China. And nobody doubts that Buddhism originally reached China from India ("the West").

I don't think "political order differences" makes sense as a distinguishing mark. Over the last 2500 years there's been theocracy, hereditary monarchy, various kinds of democracy, military dictatorship, etc., in both the East and the West, however you define them.