Karakorum
From Tardis Wiki, the free Doctor Who reference
Karakorum, (PROSE: Marco Polo) also spelled Qaraqorum, was the capital of the Mongol Empire in the year 1240. (PROSE: Bunker Soldiers) It was built upon the great steppes and consisting of tents. By 1289, the Imperial Palace had been built in Peking, which became the new capital of the empire. The Mongols living in Karakorum then dispersed, leaving the city abandoned.
In 1289, Noghai moved his army from Samarkand to Karakorum in preparation for an attack on Kublai Khan. (TV: Marco Polo)