But the vision could be pleasing. You would turn a corner and come upon a park gleaming green in the late autumn sunshine, with animals apparently roaming loose: squirrels, ermine, deer, even stags. A river ran right through the city, and people walked its banks and crossed delicate bridges. The people were both Cathay and Mongol, the latter in their colourful silk tunics and coats. People spoke Mongol, or one of the tongues of Cathay, or a rapid language that Uzzia identified as Persian, a common tongue for the traders who came here.

Some of the grander folk went on horseback. The cultured Cathay folk seemed to flinch at seeing horses inside a city, but the Mongols’ bond with their animals was indissoluble. Avatak saw one man ride along under a canopy of gold, carried by bearers who had to run alongside. Uzzia said this was probably a baron, one of the Khan’s top generals, who would command a hundred thousand men or more.

In one place by the river Avatak saw a tower, four or five times taller than a man, with a small waterwheel at its side. On the top was a brass construction, a ring showing the constellations, models of sun and moon. It was a representation of the sky, driven by the waterwheel, like a tremendously expanded version of Pyxeas’ oracle. Perhaps the links between Cathay and Northland really were deep and ancient, Avatak thought.

Uzzia said she wanted to go out of the city proper and into the suburbs, where the livelier markets were to be found. So they made their way to the northern wall, heading for a gate. The gates themselves were huge, like fortresses built into the walls, each hosting hundreds of soldiers. Uzzia spoke in her cursory Mongol to the guards, ensuring they could get back in later, even without Pyxeas’ paiza in their pockets. Beyond the gate they had to pass through the city’s outer layer of defences, over a moat filled with brackish water and then to an outer wall. There seemed to be a whole army of soldiers in rough camps in the space between the walls, with heaps of weapons, herds of the Mongols’ stocky ponies. ‘Not so much a city,’ murmured Uzzia as they walked, ‘as a fortress, and designed by Kublai to be that way. Well, I suppose it is inevitable; Old Hattusa was a fortress-city too, another capital of conquerors.’