Literature Reference: 将军出紫塞，冒顿在乌贪。—— 《鼓吹曲辞 战城南》 卢照邻 The general marches out from the Purple Frontier, Modu lurks in Wutan. Source from 'War Songs of the Southern City' by Lu Zhaolin.
紫: Represents a person of authority and prestige.
塞: The fortress, the frontier stronghold.
Meaning: The Purple Frontier symbolizes the grandeur and guardianship of the borderlands.