mountain pass, ancient kuni, low ground, (kokuji)
垰 centers on a low point in the landscape: a mountain pass, a saddle between peaks, or low ground. The ancient kuni sense is a rare historical usage, but the core idea of a low passage connects the main meanings.
垰 is a kokuji (a kanji created in Japan) that combines 土 (earth, ground) with a right-side component likely derived from 上 (up) and 下 (down) or a related shape, suggesting a place where the ground goes up and down—a pass or low area.
The left side is 土 (earth), and the right side looks like a combination of up and down strokes. Picture a mountain pass where the earth rises and falls, creating a low saddle between peaks.
For たわ, imagine a mountain pass so low that it feels like a soft, bending 'tower' of earth: tower -> たわ, and the pass bends through the hills.
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