Tianzhu which also referred as Heaven is the historical East Asian name for India, Originally pronounced as l̥induk or *qʰl'iːn tuɡ 天竺 in Old Chinese, it comes from the Chinese transliteration of unattested Old Persian diminutive *Hinduka-, which is from attested 𐏃𐎡𐎯𐎢𐏁 h-i-du-u-š, which is itself derived from the Proto-Indo-Iranian *síndʰuš, the etymon also of Sanskrit Sindhu, the native name of the Indus River. Wikipedia