Dual Monarchy of Khrom-Vestria

The Dual Monarchy of Khrom-Vestria, also known as the Khrom-Vestrian Empire is a multinational state consisting of two co-equal states, the Khrom Tzardom and the Kingdom of Vestria, they are bound together in a real union. Although they rule their lands separately, they share three vital institutions: Military, foreign affairs and financial customs. Declaring war is a joint decision between the Tzar and the King. When the Khrom and Vestrian war hosts assemble, they will merge under the command of a Khrom general. They share a united stance on the international stage, but in there are cases of separate diplomacy, like in the case of a Khrom and a Vestrian representative on the Council of the Free City Shimeji. As a customs union, any tariffs or good/item restrictions or bans are empire-wide.
Khrom-Vestria is most famous for it's "Iron Belt." It's a physical and metaphorical barrier that stretches almost the entire length of the South Continent's northern coast. It is made of castles, settlements, fortifications and very difficult terrain that would impede access to the south from the Western Ocean/Grozzart/Shimeji Sea.
At Royal-Tzarist functions, the banners of both nations are flown, as there is no single national banner. Communications between the courts of KhromKharr and Almagest are connected by a long road and carried out by double messengers on horseback.