Literature Reference: East of Luoyang, worry-free, at midnight, the Tiger Pass opens. Source from 'Sending Ren Wan to Yihai'.
虎: Resembling a majestic and awe-inspiring appearance, exuding an aura of power and valor.
牢: Sturdy, robust, firmly secured.
Meaning: Tiger Pass signifies a place of strategic importance, symbolizing strength and protection.