Most commonly refers to Khiva (Хива), a UNESCO World Heritage city in Uzbekistan famous for its walled inner town Itchan Kala — a key Silk Road oasis with stunning blue-tiled madrasas. In Hindu-religion contexts, the deity Shiva is more standardly written 湿婆 (Shīpó); 希瓦 occasionally appears as a variant transliteration.
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希 (xī, 'to hope') sounds like 'shee/khee' and 瓦 (wǎ, 'tile') sounds like 'wa' — together they approximate 'Khiva' or 'Shiva'. The 瓦 'tile' character is a fitting nod to Khiva's tile-covered monuments.