Sinfar. A plane that, several aeons ago, was quite small. A single large landmass in the center of a large sea, with inhabitants of a singular culture. They had their own faiths, their beliefs, stories and myths, yet all was passed down through word of mouth as the written language had not yet been invented.
This peaceful plane however, was not treated kindly by fate.
As is often want to happen, great beings rise and fall, and during a clash of primordials aeons ago, one such being was slain, and crashed through the cosmos and into the plane of Sinfar. The impact of its body shattered the landmass that was there, scattering it across the great sea as the body sank and fused with the plane, the inhabitants of the plane now adrift from one another, gathering up into smaller cultures and groups.
With the primordials arrival, the plane began to change. Being that the primordial was an entity of chaos, lust and greed, its very essence warped and altered the once stable plane, causing it to grow constantly, wrapping around itself at the edges. The impact from the immense entity also caused the plane to "move" from its previously fixed point, becoming almost perfectly aligned with the Astral Plane, the borders between the two growing quite thin, especially so upon the open seas.
As time went on, the scattered inhabitants of the plane started to lose track of the original myths and stories, new ones rising up instead, with the names of gods and places changing from place to place. The primordials deceased body also continued to enforce its influence upon the formerly peaceful plane, calling out across the cosmology, a beacon that shone subconciously in people's minds, planting the desire to come visit the plane, the beacon even affecting portals all throughout the planar-scape, often sending unwitting visitors to the plane, with no way to leave.
Those that came to the plane willingly with a desire to return, find themselves easily capable of coming and going as they please. Those that desire to leave it permanently, find that portals tend to spring them right back to Sinfar.
As time goes on, and visitors from other planes grew more prevalent, the cultures of the scattered islands began to change, adopting customs and ideals from those that came through portals and rifts, leading to a wide variety of places and cultures all over the plane.
One such visitor, was a wise wanderer by the name of Rodrick. He learned how to use the portals upon the sea to cross the vast, normally insurmountable distances between the individual islands, in a rather short period of time, being the first person to visit different cultures and islands since the division of the planes landmass. After several years, he came to form Rodrick's Shipping Company, establishing travel-routes through the plane, allowing free travel between the islands that have been discovered, with new one's appearing from time to time.
And now, you've come here yourself. Whether through word of mouth, an accidental step through the wrong portal, a subconcious lure, or perhaps even a local living in one of the many islands about.
And your story is just beginning.