Mirai Khan ate enormously of the steak. When the hunger of the two was satisfied and the white man's pipe was alight, he turned to the Kirghiz thoughtfully. "Have you ever heard," he asked, "of the city of Sungan?" Mirai Khan, Gray gathered, was a Mohammedan, a fatalist, a skilled horse-thief, and a dweller at the edge of the Gobi, where life was gleaned from hardship. He was a man of the _yurts_, or tents, a nomad who ranged from the mosques of Bokhara to the outskirts of China. Somewhere, perhaps, Mirai Khan had an _aul_, with a flock of sheep, a dog, and even a wife and children. The Kirghiz glanced at him keenly and shook his head. "I have heard the name," he responded. "It was spoken by my father. But Sungan I have never seen." "It is a city a week's ride beyond Ansichow," persisted Gray, "in the Desert of Gobi." "That is in the sands," Mirai Khan reflected. "No game is found there, Excellency. Why should a man go to such a place?" "Have you been there?" "Does a horse go into a quicksand?" "Have you known others who went there?" "Aye, it may be." "What had they to say of the desert?" "It is an evil place." The Kirghiz nodded sleepily. Having eaten heavily, he was ready for his blanket. "Why did they call it an evil place?" "How should I know--who have not been there?" Mirai Khan yawned and stretched his stocky arms and legs, as a dog stretches. "It is because of the pale sickness, they say." Gray looked up quickly from his inspection of the fire. He had heard that phrase before. Delabar had used it. "What is the pale sickness?" he asked patiently. Mirai Khan ceased yawning. "Out in the sands, in the _liu sha_, hangs the pale sickness. It is in the air. It is an evil sickness. It leaves its mark on those who go too near. I have heard of men who went too far into the _liu sha_ and did not return." "Why?" "It is forbidden." "By the priests of the prophet?" "Not so. Why should they deal with an evil thing? Is it not the law of the Koran that a man may not touch what is unclean? The rat priests of China, who worship the bronze god, have warned us from the region. I have heard the caravan merchants say that men are brought from China and placed out in the sands, the _liu sha_." Gray frowned. Mirai Khan spoke frankly, and without intent to deceive him. But he spoke in the manner of his kind--in parables. "Three times, Mirai Khan," he said, "you have said _liu sha_. What does that mean?" The Kirghiz lifted some sand in his scarred hand, sifting it through his fingers to the ground. "This is it," he explained. "We call it in my tongue the _kara kum_--dark sands. Yet the _liu sha_ are not the sand you find elsewhere. They are the marching sands." Gray smiled. He was progressing, in his search for information, from one riddle to another. "You mean the dust that moves with the wind," he hazarded.