They were living beside the main continent where black people come from? People migrate, and honestly, most civilizations portrayed as mostly white are mostly people of colour. It does not matter if there was a person of colour in a place that did not care about skin tones, and probably was a large portion people of colour; they were on the same land mass, and frankly did not care. You are making a bad reputation for yourself by demanding sources, then dismissing them when they're given, without giving any yourself. Please learn how to have a debate, online or not.

Regardless of whether Greece was mostly people of colour or not doesn't really matter, and if it ruins a movie for someone, unless it's a large part of the lore, they're racist, usually even if it is part of the lore.