They came to a small town fortified by a stout wall of mud-brick. Beyond, the land was more arid still: the town marked the edge of desert. To enter the town the travellers had to pass through a wide gate, horses, cart and all – even the mule. There was stabling for the animals inside, and Jamil immediately did some business, selling off his horses in order to buy – what? Avatak glimpsed a new sort of beast in the shadows of the stables, taller than a horse, stately, foul-smelling. Jamil did keep the mule. Avatak wasn’t sure if he was pleased or disappointed.

They spent a few nights here. The city was full of people of diverse hues, costumes and tongues. Jamil said this was a major meeting point for traders, who routinely travelled half the world for the sake of the profit to be made through the trade between Cathay and other eastern empires and the Continent and Northland to the west. Jamil said he’d half-expected the town to be quieter than usual, because of flood, drought, plague, banditry and the coldness of the year; such things were bad for trade. On the other hand there were more migrants than usual on the trail, coming both ways – people coming from the west in the hope of finding a better life in the east, only to meet people from the east heading west with much the same ambition. These were times of turbulence. Ominously, Pyxeas pointed to heavy shipments of weapons and armour.

Jamil was waiting on a number of other traders to get ready to leave. They would travel together as a caravan – not steam-driven, but a train of beasts and people laden with goods. Avatak had never known that the word for the Northlanders’ dazzling transport system was borrowed from a much older meaning.

The morning came when Jamil’s caravan was ready – and Avatak was introduced to his camel. The beast was extraordinary. It had two fleshy humps on a back covered with dirty brown hair, and a small head mounted on a long neck, and massive teeth, and an oddly disdainful expression. When it walked on its long legs it seemed to stagger, and at first, after climbing clumsily on its back, it was all Avatak could do to hang on. More laughter from his companions.

But after a few days he saw the beast’s advantages. It had broad hoofs that would not sink into the softest sand, and could travel for days without water. And all this with the weight of a man on its back. The stink, though – the stink was high! There were times when Avatak looked back at his mule, plodding through the sand, with almost nostalgic affection.

The caravan worked its way steadily west, a party of thirty people and twice as many camels, a few horses, one mule. The desert was flat, arid, featureless, but on the horizon mountains loomed, capped with ice, a grand setting.