Dongguan (东莞; Dūnggún in Cantonese, Dōngguǎn in Mandarin) is in the Pearl River Delta region of China, about 100 km from Hong Kong. It's a major manufacturing center, producing an estimated one fifth of the world's smartphones and one tenth of the world's shoes. Besides industrial activity, it was known for the dubious distinction of being China's prostitution capital, though this service has become much less prominent following a major crackdown in 2014.