By the time the stories set in Fenstre with Seusea and Thenson Trowheald etc, have occurred, this land is essentially uninhabited. But thousands of years prior to these events, Marnopyre was the centre of civilised Fels. It is the setting of what is probably the most ambitious tale I've ever attempted to write.
Marnopyre is a smallish continent approximately the size of Western Europe (from Poland or so westward to the Atlantic Coast) that lies off the north-eastern coast of the Three Rivers continent. This map gives a rough location, but it's inaccurate with regards to position and size, etc. It is bounded on the south by the Sea of Marnopyre, the east by Oceanicus and the north by the North-eastern Waters. It is separated from the Three Rivers, at the eastern point of the Beak of Corovan by a chain of islands called (collectively) the Grand Steps and a body of water called the Inners.
Its position in the world affords it a cool temperate maritime climate mostly, though the northern coast has a sub-arctic climate.
Marnopyre is the name of the island continent and at no time has it ever been a political entity in its own right. Ever since its founding in the semi-mythical Settlers era, it has been a collection of varied nations, the names and territories of which have altered over the years.