Hangzhou, (TV: The Gathering [+]John Fay, Torchwood series 4 (Starz, 2011).) or Han-Chow, was a city located in China, or, as Marco Polo knew it, "Cathay".
When boasting to Marco Polo about his knowledge of Cathay, the First Doctor mentioned that Han-Chow was where the finest silks were spun and woven. (PROSE: Marco Polo [+]John Lucarotti, adapted from Marco Polo (John Lucarotti), Target novelisations (Target Books, 1985).)