Left sheep radical - pictograph of a ram's horned head viewed from the front. Indexes 羯 in the ovine family with 羚 antelope, 羔 lamb, 群 flock. 羯 specifically names a castrated ram (a wether), so the sheep radical carries the full semantic load.
Right side 曷 supplies the sound - hé drifted to jié through the well-attested h/j alternation seen in 葛-knot, 揭 jiē/jié to lift. Same phonetic appears in 渴 thirsty, 喝 to drink, 谒 to call upon. Purely phonetic here, no semantic flavour carried over.
