Agreed, but there should be some justification for the inclination of the Essosi to dismiss Westeros as unimportant - and it's hard to see such a justification if Essos consists of no more than a handful of regions gathered around the Dothraki Sea and Red Waste, considering the point you make yourself below about Westeros being (well, until a few years before the "present" time, anyway...) a single country. With the geography looking like that, it's hard to see how a united Westeros doesn't easily dominate the Free Cities, or could even interfere as far away as Slaver's Bay or Ibben.

Seems like we agree that Essos needs to be much bigger, then.

Agreed. There are some signs of Westerosi power and influence stretching abroad - the presence of Jalabhar Xho at the King's Landing court, for instance - but only small ones. You'd expect more.

Or, and as you can tell I like that idea better, we just haven't been told about the northern parts of Essos (well, I thought of Ibben as part of Essos in my head, but if its distance to the mainland on those maps is justified, it probably shouldn't count as part of any continent). Credible world-building in fantasy entails, in my view, that there are some places in your world that get a lot of attention, and others that are never even mentioned, or not more than once - like Middle-Earth, I guess. It shouldn't be like Eddings, who creates a world and then feels obligated to have his characters visit every place in it.

Obviously a fan-made map couldn't contain places that aren't mentioned in the books, I'm just saying I hope that the author-approved maps do include those. Or, perhaps even better, make clear that there are parts of Essos and Sothoryos that aren't on the maps, or even other continents.