Hydronia the Great was the territory governed by the Hidronis Grand Monarchy from 1997BC till 12AD. It was the capital of the monarchy, founded by king Rodharin and was at one point a famed trading centre as well as having the Nexus within in its northern territory, making a very important spiritual destination, the "Holy Land" of the Xanjin Technologist Imperium among other empires. When the capital of Catharsis fell in 14AD, the monarchy spiraled into social, economic and cultural decline with most of it's people emigrating to foreign countries.
Much later, Rome and Hydronia declared war on Greece simultaniously, ultimately ending with the dissolution of Hydronia. Hydronia is now divided into the Upper Ptolemaic Polis, Lower Ptolemaic Polis, and Nubian Polis under New Greece, and Shanjiro under the Xanjin Technologist Imperium.
See also: Greco-Hydronian War
Much of Hydronia is covered in desert. The Nile River runs through to create seemingly inexhaustible resources, allowing civilizations to flourish in the area.