The nation had gathered around Otrar, holding it in a fist. In normal times, the idea of the khan’s sons running a race would have been an event for the warriors. They would have wagered fortunes on which brother would be first to touch the walls of the city. In the end, when Jochi staggered in, with Chagatai some way behind, their arrival went almost unnoticed. The nation waited for news that the camp was safe and every man there had parents, wives or children. Jochi’s tuman had not met his eyes when he caught sight of the tiger skin draped across his horse. The beast’s dried head had been roughly hacked from it, the sole sign that Genghis had not forgotten his sons fighting in front of the ranks. Jochi had fingered the torn skin in silence for a time, then turned away.

When the first riders came a day later, the tumans reeled at the news, everything they had feared. For a time, they were left with hope that their families might have been spared, but Khasar arrived with the survivors and the dead. Warriors ran to each cart as it came in, searching for their wives and children. Others waited in silent agony as the weary women passed them, desperate for a face they knew. Some were rewarded by a sharp cry and an embrace. Most were left standing, alone.

It took more than a month to collect every fallen warrior on the path back through the hills in the south. The Arabs were left to rot, but those who had fought for Genghis were brought in and treated with honour. Their bodies were stripped of armour and wrapped in soft white felt before being taken on carts to the highest peaks they could see and laid out for the hawks and eagles of that realm. The women who had died were tended by their sisters and mothers, with Chakahai, Borte and Hoelun overseeing the grim work.

Genghis had come to view the dead face of his sister when she was brought in. She had been found naked, with her throat cut in one great slash. His grief had been terrible to see. It was one more crime to bring to the feet of the shah. His mother had aged overnight at the news, so that Hoelun seemed constantly dazed and had to be taken by the arm wherever she went. She had lost a son many years before and ancient wounds bled again, leaving her ruined with tears. When Genghis turned his gaze on Otrar, those who saw knew the city would be reduced to dust in a hot wind.

The catapults had been destroyed on their hill, deliberately set on fire as the Otrar garrison broke out and raced away to their own destruction. Twelve good men had been found around the charred timbers, cut down as they held their posts to the last. Genghis had merely grunted when that news reached him and set his Chin artisans to making more with Koryon lumber.

The end of summer was quiet as they rested and recovered, with simmering rage always close to the surface. The city waited for them and no one came to the high walls any more, still marked with soot from the burning oil Samuka had sent against them.

Ho Sa and Samuka had been found among the heaped dead and been honoured for the enemies they had taken with them. The storytellers wove their tale into ballads for the evenings, while the empty flesh was taken with the rest, with no more ceremony than the lowest warrior of the tribes. In the distance, the peaks were covered with the dead and birds of prey hung like a dark cloud above them, feasting.

Winter in that place was a weak thing compared with the bitter cold they knew in the north. Genghis could not know the mind of the governor of Otrar, but the onset of colder months seemed to bring agitation to the city while the Mongols waited for the catapults to be rebuilt. There was no sense of urgency in the tribes. They did not need to move to live and one place was as good as any other. The city would fall and if the inhabitants suffered as they waited, that too was well deserved.

As the days grew shorter, Genghis could sometimes see distant figures on the walls, pointing and talking. Perhaps they could see the frames growing on the hill outside the city. He did not know, or care. At times he was almost listless, and even after the catapults were finished, he did not give the order, preferring to stay in his ger and drink through a black depression. He did not want to see accusation in the eyes of those who had lost their families. It had been his decision and he tortured himself with grief and fury, sleeping only when the drink made him pass out.

The gates of Otrar opened without warning on a day of grey clouds and threatening rain. The Mongol army sent up a storm of sound, beating spears and bows on shields, showing their anger in the discordant clashing. Before Genghis or his remaining generals could respond, a small group of men came walking out and the gates closed swiftly behind them.

Genghis was talking to Khasar when he heard the howl of the warriors. He walked slowly to his horse and climbed stiffly into the saddle, staring at Otrar.

Just twelve men had left the protection of the walls. As Genghis watched, he saw his warriors riding hard at them, their swords bared. He might have stopped them, but he kept his mouth firmly shut.

The twelve Arabs bore one of their number trussed between them, his feet dragging on the dusty ground. They cowered back from the warriors swirling around them and held up their free hands to show they were unarmed. To the Mongols, that too was a provocation. Any man fool enough to venture among them without a blade or bow just excited their lust to kill.

Genghis watched impassively as the warriors galloped across the face of the men’s progress. Closer and closer they rode until one of them clipped an Arab with his horse’s shoulder, sending him spinning.

The small group paused in sudden terror and Genghis could see them calling to their fallen companion as he tried to struggle up. More warriors forced them on, yipping and urging as they might a lost sheep or goat. The man was left behind and warriors dismounted to finish him.

The sound of his screams echoed from the walls of Otrar. The group of Arabs moved on, glancing back in horror. Another was knocked down with a blow from a sword hilt, so that a flap of his scalp was torn and blood covered his face. He too was left behind in a welter of kicking, stabbing men. Genghis sat his horse in silence as he observed their progress.

Two Mongol women approached one of the Arabs and pulled him away from the others. He yelled something in his strange language and held both hands out and open, but they laughed at him and held him back from his companions. When they had passed, the man began to scream and this time he did not die quickly. The sounds grew in intensity, going on and on.

When there were just six left of the group, Genghis held up his hand, sitting straight-backed in the morning sun. Those who had watched for his signal pulled away from the bloodied Arabs and allowed a path to the khan. The group staggered on, pale with what they had seen. When they reached Genghis, they fell to the ground, abasing themselves before him. Their prisoner writhed in the dust, the whites of his eyes showing.

Genghis watched coldly as one of the Arabs lifted his head and spoke in the Chin language, his words slow.

‘My lord, we have come to discuss peace!’ he said.

Genghis did not reply and only looked back at Otrar, where the walls were once again black with small figures, watching. The man swallowed the dust in his throat and tried again.

‘The city council has voted to hand over our governor to you, lord. We were led into war against our will and we are innocent. We beg you to spare us and take only Governor Inalchuk, who is the author of our troubles.’

The man settled back to the dust now that the words were spoken. He could not understand why he and his companions had been attacked. He was not even sure if the khan had understood his words. Genghis gave no sign of it and the silence lengthened.