The Dwarves were the first true imperialists on the Three Seas. A thousand years ago, the Dwarves were a disunified nation composed of city states which dotted the northern coast of the Astreios Sea, west of Arafel. Then, under the banner of a new religion which consolidated both the gods and the cities into a Threefold Protectorate, the Dwarves began to change, and in the process to change the world with them.
Over a thousand years ago, the Protectorate was in its turn overthrown by an Emperor, Koros the Enraged, who dismantled the autonomy of the Dwarven Senate and transformed the Threefold Faith into a machine for conquest. The Protectorate became the Threefold Empire, and over the next three hundred years, each subsequent Emperor expanded the boundaries of their territory until it covered the coasts of all three of the inland seas that comprise the “known” world.
The height of the Empire was signaled by the raising of Dwarven Arafel, a city made of material even the Dwarves no longer know now to work, crossing the isthmus between the three major landmasses and creating a new capital for the Empire. The city was built during the reign of Emperor Kaganos the Lofty, who famously died when he either fell, threw himself or was thrown from the bell tower of the Cathedral of the Three at the summit of the city (much prior to the erection of the Nixor Lux).
The conquests seemed unstoppable, until they simply stopped. The reasons that the Dwarves finally stopped pushing outward are manifold and inscrutable. The short version is that they became overburdened by the administrative complexity of owning absolutely everything. The Empire deflated under its own weight, and the other races expanded to fill the gaps. The religion of the Three became unfashionable among the largely secular Dwarven aristocracy; the last emperor, Ikarion the Worthless, died under embarrassing circumstances, and the Houses simply refused to allow him to be replaced. The Minotaur corsairs rose from the northwest and coopted the old religion, and the Dwarves became, once again, a loose collection of independent polities ruled by consensus among the wealthy.
Arafel is now the only true center of Dwarven power, and even this has become a much more complicated venture, with the South and East shores of the city overrun by Dragonkin and Elves, respectively, and the Gnomes demanding reparation after a millenium of abuse. There are now Twelve Dwarven Houses in Arafel, kept together under the de facto leadership of the last Imperial scion, Dromos Kagano.