In a couple of days the smaller ships all disappeared over the horizon, and the Eight Great Ships drifted on, roped together in a perfect calm, off the maps to the unknown east. There was nothing else they could do.

Thirty days passed without the slightest breeze. Each day they rode the current farther to the cast.

No one had ever seen anything like it. Admiral Kheim rejected all talk of the Divine Calm, however; as he pointed out, the weather had gone strange in recent years, mostly much colder, with lakes freezing over that had never frozen before, and freak winds, such as certain whirlwinds that had stood in place for weeks at a time. Something was wrong in the heavens. This was just part of that.

When the wind returned at last, it was strong from the west, pushing them even farther along. They angled south across the prevailing wind, but cautiously now, hoping to stay within the hypothetical great circle current, as being the fastest way around the ocean and back home. In the middle of the circle there was rumoured to be a permanent zone of calm, perhaps the very centrepoint of the Dahai, as it was near the equator, and perhaps equidistant from shores east and west, though no one could say for sure about that. A doldrums that no junk could escape, in any case. They had to go out far enough to the east to get around that, then head south, then, below the equator, back west again.

They saw no islands. Seabirds sometimes flew over, and they shot a few with arrows and ate them for luck. They fished day and night with nets, and caught flying fish in their sails, and pulled in snarls of seaweed that grew increasingly rare, and refilled their water casks when it rained, setting funnels like inverted umbrellas over them. And they were seldom thirsty, and never hungry.

But never a sight of land. The voyage went on, day after day, week after week, month after month. The rattan and the rigging began to wear thin. The sails grew transparent. Their skin began to grow transparent.

The sailors grumbled. They no longer approved of the plan to ride the circle of currents around the great sea; but there was no turning back, as Kheim pointed out to them. So they passed through their grumbling, as through a storm. Kheim was not an admiral anyone wanted to cross.

They rode out storms in the sky, and felt the rocking of storms under the sea. So many days passed that their lives before the voyage grew distant and indistinct; Nippon, Taiwan, even China itself began to seem like dreams of a former existence. Sailing became the whole world: a water world, with its blue plate of waves under an inverted bowl of blue sky, and nothing else. They no longer even looked for land. A mass of seaweed was as astonishing as an island would once have been. Rain was always welcome, as the occasional periods of rationing and thirst had taught them painfully their utter reliance on fresh water. This mostly came from rain, despite the little stills that I Chen had constructed to clarify salt water, which gave them a few buckets a day.

All things were reduced to their elemental being. Water was ocean; air was sky; earth, their ships; fire, the sun, and their thoughts. The fires banked down. Some days Kheim woke, and lived, and watched the sun go down again, and realized that he had forgotten to think a single thought that whole day. And he was the admiral.

Once they passed the bleached wreckage of a huge junk, intertwined with seaweed and whitened with bird droppings, barely afloat. Another time they saw a sea serpent out to the east, near the horizon, perhaps leading them on.

Perhaps the fire had left their minds entirely, and was in the sun alone, burning above through rainless days. But something must have remained – grey coals, almost burnt out – for when land poked over the horizon to the cast, late one afternoon, they shouted as if it was all they had ever thought of, in every moment of the hundred and sixty days of their unexpected journey. Green mountainsides, falling precipitously into the sea, apparently empty; it didn't matter; it was land. What looked to be a large island.

The next morning it was still there ahead of them. Land ho!

Very steep land, however, so steep that there was no obvious place to make landfall: no bays, no river mouths of any size; just a great wall of green hills, rising wetly out of the sea.

Kheim ordered them to sail south, thinking even now of the return to China. The wind was in their favour for once, and the current also. They sailed south all that day and the next, without a single harbour to be seen. Then, as light fog lifted one morning, they saw they had passed a cape, which protected a sandy southern reach; and farther south there was a gap in the hills, dramatic and obvious. A bay. There was a patch of turbulent white water on the north side of this majestic entrance strait, but beyond that it was clear sailing, and the flood tide helping to usher them in.

So they sailed into a bay like nothing any of them had ever seen in all their travels. An inland sea, really, with three or four rocky islands in it, and hills all around, and marshes bordering most of its shores. The hills were rocky on top but mostly forested, the marshes lime green, yellowed by autumn colours. Beautiful land; and empty!

They turned north and anchored in a shallow inlet, protected by a hilly spine that ran down into the water. Then some of them spotted a line of smoke rising up into the evening air.

'People,' I Chen said. 'But I don't think this can be the western end of the Muslim lands. We haven't sailed far enough for that, if Hsing Ho is correct. We shouldn't even be close yet.'

'Maybe it was a stronger current than you thought.'

'Maybe. I can refine our distance from equator tonight.'

'Good.'

But a distance from China would have been better, and that was the calculation they could not make. Dead reckoning had been impossible during the long period of their drift, and despite I Chen's continual guesses, Kheim didn't think they knew their distance from China to within a thousand li.

As for distance from equator, I Chen reported that night, after measuring the stars, that they were at about the same line as Edo or Beijing a little higher than Edo, a little lower than Beijing. I Chen tapped his astrolabe thoughtfully. 'It's the same level as the hui countries in the far west, in Fulan where all the people died. If Hsing Ho's map can be trusted. Fulan, see? A harbour called Lisboa. But there's no Fulan chi here. I don't think this can be Fulan. We must have come upon an island.'

'A big island!'

'Yes, a big island.' I Chen sighed. 'If we could only solve the distancefrom China problem.'

It was an everlasting complaint with him, causing an obsession with clockmaking; an accurate clock would have made it possible to calculate longitude, using an almanac to give the star times in China, and timing from there. The Emperor had some fine timepieces in his palace, it was said, but they had no clock on their ship. Kheim left him to his muttering.

The next morning they woke to find a group of locals, men, women and children, dressed in leather skirts, shell necklaces, and feather headdresses, standing on the beach watching them. They had no cloth, it appeared, and no metal except small bits of hammered gold, copper and silver. Their arrowheads and spear tips were flaked obsidian, their baskets woven of reeds and pine needles. Great mounds of shells lay heaped on the beach above the high tide mark, and the visitors could see smoke rising from fires set inside wicker hovels, little shelters like those the poor farmers in China used for their pigs in winter.

The sailors laughed and chattered to see such people. They were partly relieved and partly amazed, but it was impossible to be frightened of these folk.

Kheim was not so sure. 'They're like the wild people on Taiwan,' he said. 'We had some terrible fights with them when we went after pirates in the mountains. We have to be careful.'