The Pearl River is the second longest river in the world, and it feeds into the Jasmine River. The Pearl and its tributaries form the principal transportation system for the more remote regions in the Jade Taiga and the Forest of Chin that are far from any Imperial Highways. The border between the Jade Taiga and the Forest of Chin has been one of the most stable in history, as it almost always has followed the Pearl River over the entire length of the border.
The Pearl River proper originates somewhere in the Hidden City, although some of its volume is contributed by tributaries with their headwaters in the Forest of Chin, the Jade Taiga, and even the easternmost foothills of the Roof of the World. The Pearl River can be divided into five zones:
- The Source of the Pearl. This is presumably somewhere in the Hidden City.
- The Upper Pearl. This short section runs almost due south until the Kyakuchu Rapids, where it turns sharply to the west.
- The Middle Pearl. This is the longest section, describing an elliptical arc through the center of the Empire. In the Hidden City there are several unnavigable rapids through sheer-faced granite canyons, but as it continues, the terrain becomes less rocky, the river widens, and it becomes much more useful for both transport and irrigation.
- The Lower Pearl. Here the Pearl slows down and meanders languidly through a lush alluvial plain.
- The Confluence of Perfection. The City of Spires overlooks the joining of the two great rivers of the world.
The Pearl River is the site of the annual Spirit of the Eel swimming competition between the finest swimmers in the Taiga and the Forest.