Yang Bao is the capital of the Xeng Empire.
Flowing from the basin at Froststream is a large river known as the River Da-Chuan. The river then empties out into Lake Hu. The banks of the river are fertile for farming making it an ideal location to not only build a civilization, but trade with others as well.
Yang Bao is situated around Lake Hu which serves as a ready source of water amongst the ice desert. Located on Quan Island at the center of the city is the Imperial Palace, a tall pagoda-like structure, and the single tallest building in Shuang. Quan Island is connected to the mainland via a drawbridge.
Extending in a rectangular shape for many miles around the entirety of Lake Hu as well as the city is the Fortress Wall 20 feet in width. Scattered across are numerous watchtowers with archers. Magitek cannons are stationed all across the wall, as well as beacon torches. Whenever word of enemy invasion goes out, these beacons get lit, alerting the main city of the threat. Should the walls ever be breached, the population can evacuate to Quan Island and raise the drawbridge.
Yang Bao can also be entered via river. There are two entry points that connect to Lake Hu. Gate-like gratings that slide in and out can be selective as to which ships can pass through.
Not only would barbarians have to cross through many miles of ice desert to reach Yang Bao, but they would have to figure out a way to breach the Fortress Wall. The easiest way to do so is through one of the four main gates which are weak at the hinges, but those areas are the most heavily guarded. As a result, Yang Bao has a reputation for being considered "impenetrable", because the barbarians have yet to find an efficient way to launch an invasion.