易京 / Yijing Fortress
易京 / Yijing Fortress enters the wiki through Hanji 998 as 公孙瓒’s defensive stronghold at 易县. The episode describes deep trenches, mounded platforms, high towers, a central tower, iron gates, and the storage of enough grain to wait for the world to settle.
The wiki treats Yijing as the source case for 筑城避世安全幻觉. It gives Gongsun Zan physical separation but also cuts him off from generals, guests, warriors, advisers, and ordinary command flow. Documents have to be raised by rope and orders shouted through trained women, making the fortress a command-isolation device as much as a defensive structure.