Ogedai shrugged. 'Better than I had hoped. With the new powder mix, Khasar is convinced our guns have the range of the Sung cannon.' He clenched his fist at the thought, his expression fierce. 'That will make a difference, Sorhatani. We will surprise them one day. I only wish I could get some of them out to Tsubodai, but it would take years to drag those heavy things so far.'

'You are getting stronger,' she said, smiling.

'It's the wine,' he replied.

Sorhatani laughed. 'It's not the wine, you great drunkard, it's morning rides like this one and bow work each afternoon. You already look a different man from the one I found in that cold room.' She paused, tilting her head.

'There's a little more meat on you as well. Having Torogene back is good for you, I think.'

Ogedai smiled, but the excitement of the great guns was fading and his heart wasn't in it. He sometimes thought of his fears as a dark cloth that draped itself over him, choking off his breath. He had died on that campaign, and though the sun shone and his heart still beat in his chest, it was hard to go on with each day. He had thought Tolui's sacrifice might have given him fresh purpose, but instead he felt the loss as another burden, one too great to bear. The cloth still clung to him, for all Sorhatani had done. He could hardly explain it and part of him wished the woman would leave him alone to find a quiet path onwards.

Under Sorhatani's watchful gaze, Ogedai sat with the family, drank the tea and ate the cold food they had brought. No one brought him wine, so he rummaged for a skin of it in the packs, drinking straight from the teat, like airag. He ignored Sorhatani's expression as the red liquid brought a glow back to his cheeks. Her eyes seemed made of flint, so he spoke to distract her.

'Your son Mongke is doing well,' he said. 'I have reports from Tsubodai that speak highly of him.'

The other sons sat up in sudden interest and Ogedai wiped his lips, tasting the wine. It seemed bitter that day, sour on the tongue as if there was no goodness in it. To his surprise, it was Kublai who spoke, his tone respectful.

'My lord khan, have they taken Kiev?'

'They have. Your brother was part of the battles around that city.'

Kublai seemed to be struggling with impatience.

'Are they at the Carpathian mountains yet then? Do you know if they will breach them this winter?'

'You will tire the khan with your chatter,' Sorhatani said, but Ogedai noticed she still looked for an answer.

'The last I heard, they are going to try and cross before next year,' he said.

'That's a hard range,' Kublai murmured to himself.

Ogedai wondered how a young man could presume to know anything of mountains four thousand miles away. The world had grown since he was a boy. With the chains of scouts and way stations, knowledge of the world was flooding into Karakorum. The khan's library already contained volumes in Greek and Latin, full of wonders he could hardly believe. His uncle Temuge had taken the task of building its reputation seriously, paying fortunes for the rarest books and scrolls. It would be the work of a generation to translate them into civilised languages, but Temuge had a dozen Christian monks working on the task. Lost in a reverie, Ogedai dragged himself back and considered the words that had led him to drift away in thought. He wondered if Kublai was worried for his brother's safety.

'With Baidur, Tsubodai has seven tumans and forty thousand conscripts,' he said. 'The mountains will not stop them.'

'And after the mountains, my lord?' Kublai swallowed, trying not to irritate the most powerful man in the nation. 'Mongke says they will ride all the way to the sea.'

The younger brothers hung on his response and Ogedai sighed. He supposed distant battles were exciting compared to a life of study and quiet in Karakorum. Sorhatani's sons would not stay in the nest of stone for long, he could see.

'My orders are to secure the west, to give us a border without enemies clamouring beyond it to invade our lands. How Tsubodai chooses to do that is up to him. Perhaps in a year or two you will travel out to him. Would you like that?'

'Yes. Mongke is my brother,' Kublai replied seriously. 'And I would like to see more of the world than just maps in books.'

Ogedai chuckled. He could remember when the world seemed limitless and he had wanted to see it all. Somehow, he had lost that terrible hunger and for a moment he wondered if it was Karakorum that had taken it from him. Perhaps that was the curse of cities, that they rooted nations in one place and made them blind. It was not a pleasant thought.

'I would like to have a private word with your mother,' he said, realising he would not have a better moment that day.

Kublai moved fastest, shepherding his brothers to their horses and taking them in the direction of Khasar's gun teams, still practising in the afternoon sun.

Sorhatani sat down on the mat of felt, her expression curious.

'If you are going to declare your love for me, Torogene told me what to say,' she said.

To her pleasure, he laughed aloud. 'I'm sure she has, but no, you are safe from me, Sorhatani.' He hesitated and she leaned closer, surprised to see a touch of pink come to his cheeks.

'You are still a young woman, Sorhatani,' he began.

She shut her mouth rather than reply, though her eyes sparkled. Ogedai began twice more, but stopped himself.

'We have established my youth, I think,' she said.

'You have your husband's titles,' he went on.

Sorhatani's light mood dropped away. The one man who could remove the extraordinary authority she had been given was nervously trying to say what was on his mind. She spoke again, her voice harder.

'Earned by his sacrifice and death, my lord, yes. Earned, not given as a favour.'

Ogedai blinked, then shook his head.

'They too are safe, Sorhatani,' he said. 'My word is iron and you have those things from my hand. I will not take them back.'

'Then what is sticking in your throat so that it chokes you to say it?'

Ogedai took a deep breath. 'You should marry again,' he said.

'My lord khan, Torogene told me to remind you…'

'Not to me, woman! I've told you before. To my son. To Guyuk.'

Sorhatani looked at him in stunned silence. Guyuk was the heir to the khanate. She knew Ogedai too well to think the offer was made in haste. Her mind whirled as she tried to see through to what he truly wanted. Torogene must have known the offer would be made. Ogedai would never have thought of it on his own.

The khan turned away from her, giving her time. As he stared into the middle distance, the cynical part of Sorhatani wondered if this was a way to bring her husband's vast holdings back into the khanate. At a stroke, marriage to Guyuk would reverse the rashness of Ogedai's offer to Tolui. The effects of that unique decision were still rippling out and she did not know where it would end. The original lands of Genghis Khan were ruled by a woman and she had still barely come to terms with it.

She thought of her own sons. Guyuk was older than Mongke, but not by many years. Would her sons inherit, or would their birthright be stolen from them in such a union of families? She shuddered and hoped Ogedai had not seen. He was the khan and he could order her to marry, just as he had given her the titles of her husband. His power was near absolute over her, if he chose to use it. She looked at him without turning her head, weighing up the man she had nursed through fits and darkness so strong that she had thought he would never return. His life was as fragile as porcelain, yet he still ruled and his word was iron.

She could sense his patience was unravelling. A small muscle fluttered in his neck and she stared at it, searching for words.

'You do me great honour with such an offer, Ogedai. Your son and heir…'