Genghis looked down on the city, enjoying the sense of having it almost in his grasp. If he had been governor of such a place, he would have had the hill levelled rather than give an enemy any advantage. Yet he could not enjoy it. Thirty miles to the east, his own camp was protected by his brother Khasar, with just two tumans. The rest of them had sallied into the field against Otrar. Before the far scouts had ridden in, he had been confident that the walls could be broken.

That morning, his scouts had reported a huge army coming from the south. More than two men for every one of his eighty thousand were marching towards that position and Genghis knew he must not be caught between Otrar and the shah’s army. Around him on the crest, twelve men drew maps and made written notes on the city. Led by Lian, a master mason from a Chin city, still more worked on assembling catapults and piling clay pots of fire oil. Lian too had been confident before the shah’s army had been sighted. Now the decisions would be military and the mason simply spread his hands when any of his workers asked what the future held.

‘I’d let the governor of Otrar rot in his city if he didn’t have twenty thousand to hit our rear the moment we move,’ Genghis said.

His brother Kachiun nodded thoughtfully as he turned his horse on the spot.

‘We can’t bar the gates from the outside, brother,’ Kachiun replied. ‘They would let men down on ropes and pull the beams away. I can stay here while you take the army to meet our enemy. If you need reserves, send a scout and I’ll come.’

Genghis grimaced. The warriors of Jebe and Jochi had vanished into the valleys and hills, with no sign or contact. He could not leave the families in his camp without protection and he could not let Otrar go free with so many men. Yet if the scouts were right, he would face a hundred and sixty thousand with only six of his ten tumans. No one had more faith in the fighting ability of his warriors than Genghis himself, but his spies and reports said that this was only one of the shah’s armies. Genghis not only had to crush it, but come through without serious losses, or the next army would end it all. For the first time since coming west, he wondered if he had made a mistake. With such a vast force available to him, it was no wonder the governor of Otrar had been so arrogant.

‘Have you sent men out looking for Jochi and Jebe?’ Genghis demanded suddenly.

Kachiun bowed his head, though the khan had asked the question twice already that morning.

‘There is still no sign. I have scouts riding a hundred miles in all directions. Someone will bring them in.’

‘I would expect Jochi to be absent when I need him, but Jebe!’ Genghis snapped. ‘If I ever needed Arslan’s veterans it is now! Against so many, it will be like throwing pebbles into a river. And elephants! Who knows how we can stand against those beasts?’

‘Leave the camp undefended,’ Kachiun said.

Genghis glared at him, but he only shrugged.

‘If we fail, two tumans would not be enough to get them home. The shah would fall on them with everything he has left. The stakes are already that high, just by being here.’

Genghis did not reply as he watched the spars of a catapult being lifted into position. If he had a free month, two at most, he could smash his way into the city, but the shah would never give him such a respite. He scowled at the choices. A khan could not throw bones with his entire people, he told himself. The risk of being crushed between hammer and anvil was too great.

Genghis shook his head without speaking. A khan could do as he pleased with the lives of those who followed him. If he gambled and lost, it would be a better life and death than raising goats on the plains of home. He still remembered how it had been to live in fear of the sight of men on the horizon.

‘When we were at the walls of Yenking, brother, I sent you out to bleed a Chin column. We know where the shah is heading and I will not wait in patient squares and columns for him to come to us. I want his men under attack all the way to Otrar.’

Kachiun raised his head when he saw the glitter come back to his brother’s eyes. He took a scout map from a servant’s arms and unrolled it on the ground. Genghis and his brother crouched over it, looking for terrain they could use.

‘With so many men and animals, he will have to split his force here and here, or bring them through this wide pass in one group,’ Kachiun said. The land to the south of Otrar was a rough plain of farms and crops, but to reach it, the shah had to cross a range of hills that would funnel the Arabs into a long column.

‘How long before they reach the passes?’ Genghis asked.

‘Two days, maybe more, if they are slow,’ Kachiun replied. ‘After that, they are on open farmland. Nothing we have will stop them.’

‘You cannot guard three passes, Kachiun. Who do you want?’

Kachiun did not hesitate.

‘Tsubodai and Jelme.’

The khan looked at his younger brother, seeing his enthusiasm kindle.

‘My orders are to thin them, Kachiun, not fight to the death. Hit and retreat, then hit them again, but do not let them trap you.’

Kachiun bowed his head, still staring at the map, but Genghis tapped him on the arm.

‘Repeat the order, brother,’ he said softly.

Kachiun grinned and did so.

‘Are you worried I will not leave enough for you?’ he said.

Genghis did not answer and Kachiun looked away, flushing. The khan stood and Kachiun rose with him. On impulse, his brother bowed and Genghis accepted the gesture with a dip of his head. Over the years, he had learned respect came at the cost of personal warmth, even with his brothers. They looked to him for answers to all the problems of war, and though it made him a remote figure, it was a part of him and no longer a mask.

‘Send for Tsubodai and Jelme,’ Genghis said. ‘If you delay the shah long enough, perhaps Jochi and Jebe will support you. They too are yours to command. You have half my army, brother. I will be waiting here.’

He and Kachiun had come a long way from the young raiders they had once been, Genghis thought. Ten generals would stand to face the shah’s army and Genghis did not know whether they would live or die.

Chakahai came out of her ger to see what the sudden shouts meant. She stood in the hot sun with her Chin servants shading her skin and she bit her lip when she saw the warriors coming out of their homes with supplies and weapons.

Chakahai had lived among the Mongols for long enough to know it was not just a scouting group that was forming. All the men but Khasar and his second, Samuka, were away at the city to the west and she bit her lip in frustration. Ho Sa would be with Khasar, of course, but surely Yao Shu would know what was happening. With a curt order, she started her servants moving with her, seeking out the Buddhist monk as the camp grew noisier all around. She could hear women screeching in anger and she passed one who was weeping on the shoulder of a young man. Chakahai frowned to herself, her suspicions hardening.

She passed the ger of Borte and Hoelun before she caught a glimpse of the monk. Chakahai hesitated outside, but the decision was made when Borte came out, flushed and angry. The two wives of Genghis saw each other at the same time and both stood stiffly, not quite able to put aside the strain they felt.

‘Do you have news?’ Chakahai spoke first, deliberately giving the older woman honour. It was a small thing, but Borte’s shoulders became less rigid and she nodded. Chakahai saw how weary she was as she spoke.

‘Genghis is taking the tumans,’ Borte said. ‘Khasar and Samuka have orders to leave at noon.’

One of Chakahai’s servants made a terrified sound and Chakahai reached out instantly, slapping the girl’s face. She turned back to Borte, who was already staring across the camp at the men gathering in ranks.