Sinju
From Tardis Wiki, the free Doctor Who reference
Sinju was a town in 13th century China. (TV: Marco Polo). It is speculated that Sinju was located in the current region of either Xining (西宁) or more likely, Yangzhou (扬州). This is a major inaccuracy in the story's geography, since the rider from Shang-tu apparently covers three hundred miles in 24 hours, neglecting at minimum a further thousand kilometers, since Shang-tu is very remote from either location.