Oasis (Marco Polo)

From Tardis Wiki, the free Doctor Who reference

In 1289, the First Doctor, Susan Ian, and Barbara arrived at a small oasis in the Gobi Desert, as they were travelling from Lop to Tun-Huang, with the ultimate destination being Peking. The oasis was a dangerous place for travellers to visit, owing to bandits that often camped nearby. (TV: Marco Polo)

The Oasis was located 30 leagues away from the city of Tun-Huang in the south-east. (PROSE: Marco Polo)