I'm talking about how, for example, during Ptolemic Egypt, Greeks immigrants that lived in Egyptian cities like Alexandria and Krokodilopolis viewed Egyptians Gods. Did they saw them as equivalents of Greek Gods? (like: Athena=Thot or Amon=Zeus, Dionysus=Osiris or Hephaestus=Ptah) or did they see them as "false gods" as how monotheistic religions views pagans today? In that case how can we explain the existance of some Greco-Egyptian gods like Serapis that were "created" during that area, in Egypt, to accommodate the beliefs of both Greek and Egyptian culture in order to avoid potential conflics?

The Egyptians Gods vs the Greek Gods was just example, there were a lot of other examples clash of civilizations in other places like in Europe with the Gallic gods vs the Roman Gods, the Zoroastrian Gods vs the ancient Arab Gods, the Roman Gods vs the Greek Gods, etc. So How polytheists in ancient times, traditionally, viewed gods of the other pantheons?