Fairyland
There was a time when the world was not round. If you sailed far enough in any one direction then you would eventually run into a barrier of some sort. To the east it would be the end of the great inland sea; caravans arriving from even further east told of an immensity of land stretching off seemingly forever, eventually reaching the other side of the world. But these lands were occupied by hostile peoples and, without sail, there was no way to explore them.
To the south it got progressively hotter and the storms progressively worse until you would reach a point where a wise captain would turn back. And all the while you would be skirting the southern lands; a dangerous place with whom there was generally war, though not for some years.
No one sailed north. Anyone sailing north never returned. It was generally assumed that the warlike barbarians who lived there and occasionally harrassed civilization caught, killed, and then who could say what they ultimately did to those venturing north. The north was its own barrier.
That left the west. Shipping was common to the west; in fact, if one sailed far enough west then one could sail south in relative safety to trade for the riches to be found there. But the west had its own riches; cod mostly. Without salted cod no one could sail anywhere for long, and cod was the thing most in demand to the south for which they paid in rum. No one could sail anywhere for long without grog either.
One could sail for a very long time in a westerly direction, but not forever. Eventually, as was well known, one would reach the end of the ocean. The end of the western ocean was a vast waterfall falling into the abyss. Enroute there were fantastic sea monsters and unnatural storms; strange new lands and stranger inhabitants. Most of a map showing the extremeties of 'west' would be labelled Thar Be Dragons. But not the entire map.
On the very best, that is to say, the oldest maps, the ones with unsavoury stories of their own, there would be one more island listed. Far to the west, after the dragons and the storms, but shortly before the abyss. On the very edge of the left-hand side. Often, usually in fact, in quite different places depending upon which map had made it into your possession, and exactly what its story had been. This island was called Tír na nÓg on the oldest maps; Brendan's Island on newer ones. Colloquially it was referred to as The Promised Land of the Saints. Or quite often, simply Promise.
But all maps agreed, in this modern age of knowledge, that the dragons, the storms, the strange new lands, unexplored islands and the edge of the world were all far to the west of the westernmost outpost of civilization. The place where any serious adventure truly started. Fairyland.