The governor had been gagged as well as tied. Genghis heard the moan of muffled words and gestured to Khasar to cut the gag. His brother was not gentle and the blade sliced across Inalchuk’s lips as the cloth parted, making him cry out and spit blood.

‘These men have no power over me!’ Inalchuk said through his pain. ‘Let me negotiate for my life, lord khan.’

Genghis had learned only a few words of Arabic and could not understand. He waited patiently while an Arab merchant was brought, one of those who spoke many tongues. The merchant arrived looking as nervous as the others lying in the dust. Genghis gestured for the governor to speak again and listened patiently to the translation into the Chin language. It occurred to him that he had better set Temuge to training more men in the task if he intended to stay long in Arab lands. It was hard to make himself care.

When he understood Inalchuk, Genghis chuckled cruelly, waving away a fly that buzzed around his face.

‘They have tied you like a sheep for slaughter and delivered you to your enemy, yet you say they have no power over you?’ he said. ‘What other power is there?’

As the interpreter stumbled through the reply, Inalchuk struggled into a sitting position and touched his bound hands to his bleeding face, wincing.

‘There is no council in Otrar, lord. These are mere traders of my city. They do not speak for one appointed by the shah himself.’

One of the Arabs began to spit an answer, but Khasar lunged at him, kicking him onto his back.

‘Be silent!’ Khasar snapped. He drew his sword and the battered Arabs followed the movement with nervous eyes. No interpretation was needed and the man did not try to speak again.

‘Spare my life and I will have six thousand oka of silver delivered to you,’ Inalchuk declared.

The interpreter hesitated over the sum and Genghis looked over to him. Under that yellow gaze, the shaking Arab merchant lowered himself to the ground with the others.

‘Lord, I do not know the word in the Chin tongue. It is a term of weight used by gold and silversmiths.’

‘No doubt he offers a great deal,’ Genghis replied. ‘He has set the value of his own life after all.’

The interpreter nodded where he lay.

‘The weight in silver of many men, lord. Perhaps a hundred, or even more.’

Genghis considered, glancing up at the walls of Otrar that still loomed over his army. After a time, he cut the air with his hand.

‘These others will be given to the women, to use as they see fit. The governor will live for now,’ he said. He caught Khasar’s surprise out of the corner of his eye, but did not respond to it.

‘Fetch Temuge to me,’ Genghis went on. ‘They are watching us on the walls of Otrar. I will give them something to see.’

His brother Temuge came quickly at the summons, barely glancing at the bloody dust, or the governor who still sat with his eyes darting from man to man.

‘How much silver do we have in the camp, Temuge?’ Genghis asked.

‘Perhaps a hundred carts of it, my lord khan,’ Temuge replied. ‘I have accounted for every coin, but I would have to bring my records if…’

‘Bring me the weight of a man in that metal,’ Genghis said. He sensed Inalchuk staring at him and smiled slowly. ‘And one of the moving forges Tsubodai brought back. I want the silver to run like water before sunset. Do you understand?’

‘Of course, lord khan,’ Temuge replied, though he did not understand at all. He hurried away to do his brother’s bidding.

The population of Otrar crowded onto the walls of the city to see what would become of the governor they had sent out to the Mongol army. They had suffered through the battle between the garrison and Samuka’s men. When the garrison had broken out at last, their mood had been jubilant. The shah was coming to relieve the city and they would be saved. Instead, the Mongol army had come back unchallenged from the south to surround them. They did not know if the shah still lived, but how could the khan sit outside their walls if he did? It had taken months for the merchants to form a council and days of secret talks before they had surprised Inalchuk in his bed and trussed him to be handed over. The Mongols had no grudge against the citizens of Otrar, only the man who had provoked them. Families stood together on the walls and prayed that they would be saved.

Before the sun set, Genghis had Inalchuk brought to within arrow shot of the walls. It was a dangerous thing to do, but he guessed rightly that the people within would not dare risk a shot at the one man who could choose to spare them. Just a hundred yards from the iron gates, he had Inalchuk kneel with his hands freshly tied in front.

The sight of the smoking forge had not been lost on the governor of Otrar. It too had been wheeled close to the walls of his city and he could smell the tang of hot metal on the breeze. He doubled his offer and then doubled it again, until Genghis told the interpreter to hold his tongue or lose it.

They made a strange group, standing alone before the city. Three burly men worked the forge bellows under Temuge’s direction. Genghis stood by the prisoner with Khasar, but the rest of the Mongol army stood back in silent ranks, watching.

At last, the forge workers nodded that the silver coins were molten, held in a cauldron of black iron. One of them dipped a stick into the liquid within. It charred on contact, while drops of silver hissed and spat. Two of the men ran long wooden poles through the cauldron handles and lifted it clear of the iron box and the white heat of charcoal and bellows.

Inalchuk moaned in terror as he saw them bring it out, heating the air to a haze above the simmering contents.

‘One hundred thousand oka of silver, lord,’ he said, sweating. The interpreter glanced up, but did not speak and Inalchuk began to pray aloud.

As the carriers came forward, Genghis stared into the bowl of liquid silver and nodded to himself.

‘Say these words to him in his own tongue,’ he said to the interpreter. ‘“I have no use for silver or gold.”’

Inalchuk looked up in desperate hope as the interpreter spoke.

‘What is he doing, my friend? In the name of Allah, tell me if I am to die!’

The interpreter held his breath for a moment, staring in sick fascination at the silver as it slopped against the sides of the iron and coated them.

‘I think that you are,’ he admitted. ‘It will at least be quick, so prepare your soul for God.’

Oblivious to the exchange, Genghis went on.

‘Accept this gift from me, Governor of Otrar,’ he said. ‘You may keep what you can hold.’

Genghis turned to Khasar, his face cold.

‘Have him hold out his hands, but be careful you are not burned.’

Khasar knocked Inalchuk down with a blow to his head that left him dazed. He mimed holding out his hands and the governor began to yell, refusing. Even a sword held to his throat would not make him raise his hands. In growing anger, Khasar took him by the elbow and shoulder and snapped a bone with his knee, as if breaking a stick. Inalchuk screamed, still struggling. Genghis nodded and Khasar walked round to break the other arm.

‘Do as they want, brother!’ the interpreter snapped. ‘You may live!’ Inalchuk heard through his madness and sobbing, held out the bound hands, one supporting the other as it hung limp. Genghis nodded to the forge men and they tipped the cauldron, slopping silver towards the edge.

A flood of bubbling metal covered the governor’s hands, so that for a moment it looked as if he held shining rain. He opened his mouth to scream, but no sound came out. His fingers were welded together in the heat, the flesh dissolving.

He fell backwards, jerking away and landing on his face, drool spilling from his mouth as his lips made a paste of dust. His eyes were blank as Genghis came to stand over him, looking with interest at hands that seemed twice their usual size.