From Mandarin Chinese 縣/县 (xiàn).
сияан • (sijaan) (Mongolian spelling ᠰᠢᠶᠠᠨ (siyan))
(This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium.)
сияан • (sijaan) (Mongolian spelling ᠰᠠᠶᠠᠩ (sayang))