"Ride to the foot of the wall, then come straight back," he said to them. The two men bowed their heads, exchanging a glance in expressionless faces. As one, they dug in their heels and called "Chuh!" to make their mounts run. Sand spattered into the air as they began their race to the foot of the black wall and Khasar and Kachiun watched through eyes slitted against the glare.

"Do you think they will reach it?" Kachiun asked.

Khasar shrugged without speaking, too intent on watching the wall.

Kachiun thought he saw a sharp gesture from the distant guard. The scouts had the sense not to ride together, taking a split path at full gallop and veering right and left to spoil the aim of any archers. For a long time, there was no sound but the echoes of their hooves, and the brothers watched with held breath.

Kachiun swore as a line of archers appeared on the wall.

"Come on," he urged under his breath. Dark specks flashed down at the two scouts riding wildly in, and Kachiun saw one of them swerve recklessly as he reached the great gate. They could see him slam his fist into the wood as he turned his mount, but the archers were loosing in waves and an instant later he and his horse were pinned with a dozen shafts. The dying man cried out and his mount began the trip back, missing a step and stumbling as it was hit again and again. They fell at last almost together, lying still on the sand.

The second scout was luckier, though he had not touched the wall. For a time, it looked as if he might escape the shafts, and Khasar and Kachiun shouted to him. Then he jerked in the saddle and his horse reared and collapsed, its legs kicking as it rolled over him.

The horse made it back to its feet and limped back to the brothers, leaving the scout's body broken behind it.

Khasar dismounted and took the loose reins. The leg was broken and the pony would not be ridden again. In silence Khasar tied the reins to his saddle. He wasn't going to leave the animal behind with so many mouths to feed in the camp.

"We have our answer, brother," Khasar muttered, "though it's not the one I wanted. How are we going to get through them?"

Kachiun shook his head. "We will find a way," he said, glancing back to the dark line of archers watching them. Some of them raised their arms, though whether in mockery or salute, he could not tell. "Even if we have to take it down, stone by stone."

As soon as Khasar and Kachiun were sighted riding alone, the forces of Genghis were halted in their tracks. Before they could reach the outer lines of mounted warriors, the brothers passed skirmisher groups who remained staring outwards at the mountains they left behind. Genghis and his officers had learned hard lessons in the years of building the tribes into a single army, and galloping boys raced ahead to tell him they were coming in.

Neither man replied to those who called to them. Grim and silent, they rode to their brother's ger, sitting like a white limpet on its cart. When they reached it, Khasar dismounted in a jump and glanced at the man who stepped forward to take the reins.

"Tsubodai," he said in greeting, forcing a smile. The young warrior seemed nervous and Khasar recalled he had been promised armor and a good horse. He grimaced at the timing.

"We have many things to discuss with the khan. Claim your horse another time."

Tsubodai's face fell with disappointment and Khasar snorted, catching him by the shoulder as he turned away. He recalled the boy's courage in leaping among the sons of the Woyela. It was a favor he could repay.

"Perhaps there will be a moment when we are done. Come with me, then, if you can be silent."

Tsubodai regained his grin on the instant, tinged with nervousness at meeting the great khan himself. With a dry mouth, he climbed the steps of the cart and followed the brothers into the shadowed interior.

Genghis was ready for them, his young messenger still panting at his side.

"Where are the scouts?" he demanded, taking in their serious expressions.

"Dead, brother. And the pass is guarded by a wall of black stone as high as a hundred gers, maybe more."

"We saw perhaps fifty archers drawn out," Kachiun added. "They were not skilled, as we know it, but they could hardly miss. The wall lies at the end of a narrow pass, a gorge between steep sides of rock. I could not see a way to flank them."

Genghis frowned, rising from his seat. He made a clicking sound in his throat as he stepped across the ger and passed out into the bright sun. Khasar and Kachiun followed him out, hardly noticing the wide-eyed Tsubodai on their heels.

Genghis stood on the blue-green sand below them, looking up. He held a stick in his hands and gestured with it, drawing a line on the ground.

"Show me," he ordered.

It was Kachiun who took the stick and drew in neat strokes. Khasar watched in fascination as his brother re-created the canyon he had seen a few hours before. To one side, Kachiun drew a copy of the arched gate and Genghis rubbed his chin in irritation.

"We could tear the carts up to make wooden shields to get men close," he said doubtfully.

Kachiun shook his head. "That would bring us to the gate against their shafts, but once we were there, they could drop stones on us. From that height, a few planks would be smashed to pieces."

Genghis raised his head, gazing over the ranks of the families to the treeless expanse of the desert in all directions. They had nothing with which to build.

"Then we will have to draw them out," he said. "A staged retreat, with valuable items left in our wake. I will send in men in the best armor and they will survive the arrows, but be driven back by them in panic, with much shouting." He smiled at the prospect. "It will teach our warriors a little humility, perhaps."

Kachiun rubbed his boot along the edge of the drawing. "It might work if we could know when they open the gate, but the canyon twists. As soon as we are out of sight, we'll have no way of knowing when they come out. If I could get a couple of boys onto the crags at the sides, they could signal to us, but it is a vicious climb and there's no cover on those rocks. They would be seen."

"May I speak, lord?" Tsubodai said suddenly.

Khasar started in indignation. "I told you to be silent. Can you not see this is important?" The gaze of all three men turned on the young warrior, and he blushed darkly.

"I am sorry. I thought of a way we might know when they come out."

"Who are you?" Genghis asked.

Tsubodai's voice wavered as he bowed his head. "Tsubodai of the Uriankhai, lord." He caught himself in embarrassment. "Of the nation, lord, I-" Genghis held up a hand. "I remember. Tell me what you are thinking."

With a visible effort, Tsubodai swallowed his nervousness and told them. It surprised him that they had not thought of it. The gaze of Genghis in particular seemed to bore into him, and he ended staring away into the middle distance.

Tsubodai suffered in silence while the three men considered. After an age, Genghis nodded.

"That could work," he said, grudgingly. Tsubodai seemed to grow a little taller.

Khasar flashed a smile at the younger man, as if he were responsible for his cleverness.

"See to it, Kachiun," Genghis said. He grinned at Tsubodai's pride. "Then I will ride to see this place you describe." His mood changed as he considered destroying some of the carts that had carried the families across the desert. With wood so scarce, each one was much mended and handed down through the generations. There was no help for it.

"Take the first ten carts you see and join the wood into a barricade that can be held and moved."

He saw Kachiun's gaze drift over the khan's ger at his back and snorted.

"Begin with the next cart you see, brother. Do not think to have mine."