Races

[Chasingstars]

You can see the Glass Ocean between Hingashi and Tural from the surface of the moon and it's just as vast as our world's Pacific Ocean. When Eitherys spins that way, the entire planet is blue. On top of that, there is no "Beringia" analogue on the world map so bridging across does not seem feasible. Plus, on the west coast of Tural you have to contend with the Fathomless Sea, which is a series of giant cracks in the planet with oceanic waterfalls covering an area that seems to be just as big as Tural itself. I don't think it's very realistic to expect sailors coming to Tural from Othard with those things in mind.

But they might not have necessarily settled there via mundane methods. The 5th Astral Era had airships and even a flying city. The 3rd Astral Era had spaceships and space stations as well as airships. But we'll probably never know for sure until EE4.

Maybe the world looked different in eras prior to the 4th calamity of earth occurred, or as you said they access to a means of travel that made it feasible. Though unless expanded further by official sources, I do admit its all just conjecture. As I personally wouldn't have even gone down that rabbit hole if it weren't for noticing the oddness with hrothgar and viera in their living locations. I personally doubt we will get more information than what we have on the 4th era.