The 囗 (enclosure) radical wraps everything inside — fitting for both meanings: an enclosed corral for horses, and an enclosed border zone of a state. The inside element 幸 hints at 'safety / fortune' kept within.
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Classical Chinese only. You will see it in 《左传》, 《周礼》, and the compound 圉人 (yǔrén, royal groom). Never used in modern speech.
