This new interest in astronomy quickly superseded all others in Khalid, and grew to a passion after Iwang brought by a curious device he had made in his shop, a long silver tube, hollow except for glass lenses placed in both ends. Looking through the tube, things appeared closer than they really were, with their detail more fine.

'How can that work?' Khalid demanded when he looked through it. The look of surprise on his face was that of the puppets in the bazaar, pure and hilarious. It made Bahram happy to see it.

'Like the prism?' Iwang suggested uncertainly.

Khalid shook his head. 'Not that you can see things as bigger, or closer, but that you can see so much more detail! How can that be?'

'The detail must always be there in the light,' Iwang said, I and the eye only powerful enough to discern part of it. I admit I am surprised, but consider, most people's eyes weaken as they age, especially for things close by. I know mine have. I made my first set of lenses to use as spectacles, you know, one for each eye, in a frame. But while I was assembling one I looked through the two lenses lined up together.' He grinned, miming the action. 'I was really very anxious to confirm that you two saw the same things I saw, to tell the truth. I couldn't quite believe my own eyes.'

Khalid was looking through the thing again.

So now they looked at things. Distant ridges, birds in flight, approaching caravans. Nadir was shown the glass, and its military uses were immediately obvious to him. He took one they had made for him, encrusted with garnets, to the Khan, and word came back that the Khan was pleased. That did not ease the presence of the Khanate in Khalid's compound, of course; on the contrary, Nadir mentioned casually that they were looking forward to the next remarkable development out of Khalid's shop, as the Chinese were said to be in a turmoil. Who knew where that kind of thing might end?

'It will never end,' Khalid said bitterly when Nadir had gone. 'It's like a noose that tightens with our every move.'

'Feed him your discoveries in little pieces,' Iwang suggested. 'It will seem as if there are more of them.'

Khalid followed this advice, which gave him a little more time, and they worked on all manner of things that it seemed would help the Khan's troops in battle. Khalid indulged his interest in primary causes mostly at night, when they trained the new spyglass on the stars, and later that month on the moon, which proved to be a very rocky, mountainous, desolate world, ringed by innumerable craters, as if fired upon by the cannon of some super emperor. Then on one memorable night they looked through the spyglass at Jupiter, and Khalid said, 'By God it's a world too, clearly. Banded by latitude and look, those three stars near it, they're brighter than stars. Could they be moons of Jupiter's?'

They could. They moved fast, around Jupiter, and the ones closer to Jupiter moved faster, just like the planets around the sun. Soon Khalid and Iwang had seen a fourth one, and mapped all four orbits, so that they could prepare new viewers to comprehend the sight, by looking at the diagrams first. They made it all into a book, another gift to the Khan – a gift with no military use, but they named the moons after the Khan's four oldest wives, and he liked that, it was clear. He was reported to have said, 'Jewels in the sky! For me!'

Who is the Stranger?

There were factions in town who did not like them. When Bahram walked through the Registan, and saw the eyes watching him, the conversations begun or ended by his passage, he saw that he was part of a coterie or faction, no matter how innocuous his behaviour had been. He was related to Khalid, who was allied with Iwang and Zahhar, and together they formed part of Nadir Devanbegi's power. They were therefore Nadir's allies, even if he had forced them to it like wet pulp in a paper press; even if they hated him. Many other people in Samarqand hated Nadir, no doubt even more than Khalid did, as Khalid was under his protection, while these other people were his enemies: relatives of his dead or imprisoned or exiled foes, perhaps, or the losers of many earlier palace struggles. The Khan had other advisers courtiers, generals, relatives at court – all jealous of their own share of his regard, and envious of Nadir's great influence. Bahram had heard rumours from time to time of palace intrigues against Nadir, but he remained unaware of the details. The fact that their involuntary association with Nadir could cause them trouble elsewhere struck him as grossly unfair; the association itself was already trouble enough.

One day this sense of hidden enemies became more material: Bahram was visiting Iwang, and two qadi Bahram had never seen before appeared in the door of the Tibetan's shop, backed by two of the Khan's soldiers, and a small gaggle of ulema from the Tilla Karia Madressa, demanding that Iwang produce his tax receipts.

'I am not a dhimmi,' Iwang said with his customary calm.

The dhimmi, or people of the pact, were those non believers who were born and lived their lives in the khanate, who had to pay a special tax. Islam was the religion of justice, and all Muslims were equal before God and the law; but of the lesser ones, women, slaves and the dhimmi, the dhimmi were the ones who could change their status by a simple decision to convert to true belief. Indeed there had been times in the past when it had been 'the book or the sword' for all pagans, and only people of the book Jews, Zoroastrians, Christians and Sabians – had been allowed to keep their faith, if they insisted on it. Nowadays pagans of all sort were allowed to keep their various religions, as long as they were registered with the qadis, and paid the annual dhimma tax.

This was clear, and ordinary. Ever since the shiite Safavids had come to the throne in Iran, however, the legal position of dhimmi had worsened – markedly in Iran, where the shiite mullahs were so concerned with purity, but also in the khanates to the east, at least sometimes. It was a matter for discretion, really. As Iwang had once remarked, the uncertainty itself was a part of the tax.

'You are not a dhimmi?' one of the qadi said, surprised.

'No, I come from Tibet. I am mustamin.'

The mustamin were foreign visitors, permitted to live in Muslim lands for specified periods of time.

'Do you have an aman?'

'Yes.'

This was the safe conduct pass issued to mustamin, renewed by the Khanaka on an annual basis. Now Iwang brought a sheet of parchment out of his back room, and showed it to the qadis. There were a number of wax seals at the bottom of the document, and the qadis inspected these closely.

'He's been here eight years!' one of them complained. 'That's longer than allowed by the law.'

Iwang shrugged impassively. 'Renewal was granted this spring.'

A heavy silence ruled as the men checked the document's seals again. 'A mustamin cannot own property,' someone noted.

'Do you own this shop?' the chief qadi asked, surprised again.

'No,' Iwang said. 'Naturally not. Rental only.'

'Monthly?'

'Lease by year. After my aman is renewed.'

'Where are you from?'

'Tibet.'

'You have a house there?'

'Yes. In Iwang.'

'A family?'

'Brothers and sisters. No wives or children.'

'So who's in your house?'

'Sister.'

'When are you going back?'

A short pause. 'I don't know.'

'You mean you have no plans to return to Tibet.'

'No, I plan to return. But – business has been good. Sister sends raw silver, I make it into things. This is Samarqand.'

'And so business will always be good! Why would you ever leave? You should be dhimmi, you are a permanent resident here, a nonbelieving subject of the Khan.'

Iwang shrugged, gestured at the document. That was something Nadir had brought to the khanate, it occurred to Bahram, something from deep in the heart of Islam: the law was the law. Dhimmi and mustamin were both protected by contract, each in their way.