tribe of Scythian nomads
狁 refers specifically to a historical tribe of Scythian nomads. It has no broader conceptual center beyond this narrow ethnic designation.
狁 combines the animal radical 犭 with 允, which likely provides the sound. The character was created to represent the name of a specific nomadic tribe.
The animal radical 犭 suggests a connection to beasts or wildness, and 允 (sincere/permit) hints at a people. Together they point to a tribe of nomads known for their animal-like fierceness.
For イン, imagine an inn (イン) on the steppe where Scythian nomads stop to rest: inn -> イン, and the inn is run by the tribe.
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