The point of the caravan line was of course trade. The Parisa–Hantilios line, the longest in the world to date, had been laid at huge expense to connect two great trading centres: Parisa, a hub for goods passing to and from Northland, Albia, Gaira, and even far Scand; and Hantilios, central to the Continent, which lay on trading routes connecting north and south, west and east. So the bulk of the caravan was freight carriages laden with lumber and coal and tin and gold from Albia, furs and amber from Scand, and barrels of Kirike-fish from Northland itself, all bound for the needy markets of the east.

It was the passenger carriages, though, that caught Avatak’s eye. In Northland such carriages were plain but functional boxes of steel and wood with sturdy windowpanes. They were even heated in winter (and increasingly in the summer too) by pipes through which steam was bled from the engine. The carriages here in Parisa, though, were topped by what looked like dome-shaped tents, covered for now by sooty leathers which boys were cleaning of grime as the passengers arrived. Avatak found the carriage they had been assigned, and clambered through a doorway, pushing aside a heavy flap. The tent was a frame of bent wooden slats heaped with vividly coloured velvet. The floor was covered with a thick carpet, and there were couches to lie on, and trunks to store your luggage and food and drink. The windows were holes in the wall covered with leather panels scraped so thin you could see through them.

Pyxeas smiled at the boy’s marvelling reaction. ‘We will be transported by Northlander ingenuity,’ he said, ‘but on the way we will live in a yurt that the Great Khan in Daidu might not be ashamed of.’ For that, it seemed, was the basis of the design of the shelter, the portable houses of the nomadic tribesmen of the plains of Asia. ‘There was a scheme to build a new caravan line east into the heart of Asia itself, perhaps all the way to Daidu. The representatives of the Khans travelled west to try out the technology.’

‘And so to snag their attention,’ Rina said cynically, ‘the engineers built these fake yurts on the back of caravan carriages, just to make the Khan’s people feel at home. A blatant bit of salesmanship, Uncle.’

Pyxeas was grumpy. ‘One must take the world as it is,’ he snapped back. ‘And anyway it worked. The pan-Asia line would have been built by now if not for the weather, and you and I, Avatak, would be travelling to Daidu in heated comfort all the way.’

Rina snorted.

Avatak, his imagination snagged by the idea of crossing an unknown country in a tent as if he was a Mongol warrior himself, could barely wait for the journey to begin.

It took a full day and night to load up the caravan. Pyxeas’ party spent the final night in their carriage, the three of them bundled up on their couches, separated by partitions of embroidered cloth. The yurt was comfortable, though not yet heated as the engine was idle. They lit their lanterns, and they had a water tank topped up by servants, even a small stove and a food store; it was a home from home, and Avatak enjoyed exploring more of its little gadgets. He slept badly that night, however, such was the racket of the loading.