Doggerland

Doggerland, an artificial island constructed by Fiyu, was a province of Hoeland. It was based off of the real-life historical region Doggerland, which sank into the sea as the result of rising sea levels around 6500 to 6200 BC.

Its most notable feat is being the largest artificial island created on the Multi Earth World.

Always under the control of its creator Fiyu, the region went from being a Hoeland province to (part of) a Roman province to a short-lived empire to a part of the Angevin Empire.