Colloquially known as "The Edges of the World", the so-called Storm Edges that are located East and West of the known continents have thwarted any attempts at further exploration of Sancstoryl. While it's known, due to mathematical calculations and spelljammers, that the World of Sancstoryl is round and much bigger than the just the known world, and that theoretically you would end up back where you came from if you went far enough east or west, the Storm Lines made the practice of this more or less impossible.
In the past and even in the present, many ambitious explorers have tried and are still trying to pass the Storm Edges, in order to make travel from the eastern to the western continents more convenient without teleportation. Most of their ships were either destroyed, or washed up in the other sides' oceans completely abandoned; not even corpses were found onboard, while all cargo and rations were still found on them. Flying ships meanwhile can't make it through the storms and will always break down.
There are many theories regarding the Storm Edges, none of which are proven. But the most popular theory is that the storm-edges hide landmasses that the gods do not want the people of our parts of Sancstoryl to find; at least not quite yet. This is supported by ancient texts from way back even before the Illiadians arrived, that mention strong storms that halted naval and aerial exploration, which is theorized to be ancient forms of the Storm Edges that kept the different continents apart until later.