Constantinople still used Roman law, and the language of the state remained Latin. But, Athalaric found, its bureaucracy was difficult, entangling, altogether more eastern. Evidently Constantinople’s engagements with the mysterious nations that lay beyond Persia in the unseen heart of Asia were influencing its destiny. At last, however, all the paperwork was arranged — even though Honorius’s dwindling supply of gold was diminished further in the process. They joined a boatload of pilgrims, mostly minor Roman aristocracy from the western lands, bound for the Holy Land. After that they traveled by horseback and camel into the deeper interior.

But as the days of their journey wore on, and Honorius grew visibly more frail and exhausted. Athalaric felt increasingly regretful that he had not, after all, persuaded his mentor to turn back at Rome.

Petra turned out to be a city of rock.

“But this is extraordinary,” Honorius said. He dismounted hastily and strode toward the giant buildings. “Quite extraordinary.”

Athalaric clambered down from his horse. Casting a glance at Papak and his porters as they led the horses to water, he followed his mentor. The heat was intense, and in this dry, dusty air Athalaric did not feel protected at all by the loose, bright white local garment Papak had provided for him.

Huge tombs and temples thrust out of a steppe so arid that it was all but a desert. It was still a bustling city, Athalaric could see that. An elaborate system of channels, pipes, and cisterns collected and stored water for orchards, fields, and the city itself. And yet the people looked somehow dwarfed by the great monuments around them, as if they had been shrunken by time.

“Once, you know, this place was the center of the world,” Honorius mused. “There was a battle for ascendancy between Assyria, Babylon, Persia, Egypt — all centered on this region, for under the Nabataeans Petra controlled the trade between Europe, Africa, and the east. It was an extraordinarily powerful position. And under Roman rule Petra grew even richer.”

Athalaric nodded. “So why did Rome come to rule the world? Why not Petra?”

“I think you see the answer all around,” Honorius said. “Look.”

Athalaric could see nothing but a few trees straggling for life among the shrubs, herbs, and grasses. Goats, tended by a ragged, wide-eyed boy, nibbled low branches.

Honorius said, “Once this was woodland, dominated by oak and pistachio trees: so say the historians. But the trees were felled to build houses, and to make plaster for the walls. Now the goats eat what remains, and the soil, overfarmed, grows dry and blows away into the air. As the land has grown poor, as the water is pumped dry, so the population flees — or starves. If Petra did not exist here already, it could never be sustained by such a poor hinterland. In another few centuries it will be abandoned altogether.”

Athalaric was struck by an oppressive feeling of waste. “What is the purpose of these magnificent heapings of stone — all the lives that must have been consumed in their construction — if the people are to eat themselves to barrenness and rain, and all is to decay to rubble?”

Honorius said grimly, “It may be that one day Rome itself will be a place of shells, of fallen monuments, inhabited by filthy people who will herd their goats along the Sacred Way, never understanding the mighty ruins they see all around them.”

“But if cities rise and fall, a man may be master of his own destiny,” Papak murmured. He had come up to them and was listening intently. “And here is one such, I think.”

A man was striding out of the city toward them. He was remarkably tall, and he wore garments of some black cloth that clung tightly to his upper body and legs. A crimson swatch enclosed his head and covered much of his face. The dust seemed to swirl around his feet. It seemed to Athalaric that he was a figure of strangeness, as if from another time.

“Your Scythian, I take it,” Honorius murmured.

“Indeed,” said Papak.

Honorius drew himself up and reached for the fold of his toga. Athalaric felt a flicker of pride, complicated by a sense of envy, or perhaps inferiority. No matter how imposing this stranger was, Honorius was a Roman citizen, afraid of no man on Earth.

The Scythian unwrapped the cloth over his face and head, scattering more dust. His face was sharp-nosed, a thing of weather-beaten planes. Athalaric was startled to see that his hair was quite blond, as yellow as a Saxon’s.

Honorius murmured to Papak, “Bid him greetings, and assure him of our best intentions to—”

Papak cut him short. “These fellows of the desert have little time for niceties, sir. He wants to see your gold.”

Athalaric growled, “We’ve come a long way to be insulted by a sand flea.”

Honorius looked pained. “Athalaric, please. The money.”

Glaring at the Scythian, Athalaric opened his wrap to reveal a sack of gold. He tossed a piece to the Scythian, who tested it with his teeth.

“Now,” whispered Honorius. “The bones. Is it true? Show me, sir. Show me—”

That needed no translation. The Scythian drew a bundle of cloth from a deep pocket. Carefully he began to unwind the cloth, and he spoke in his own liquid tongue.

“He says this is a treasure indeed,” Papak murmured. “He says it comes from beyond the desert with the sand of gold, where the bones of the griffins—”

“I know about griffins,” said Honorius tightly. “I do not care about griffins.”

“From beyond the land of the Persians, from beyond the land of the Guptas — it is hard to translate,” Papak said tightly. “His sense of who owns the land is not as ours, and his descriptions are lengthy and specific.”

At last — with a shopkeeper’s sense of timing, Athalaric thought cynically — the Scythian began to open up the wrapped bandages. He revealed a skull.

Honorius gasped and all but fell on the fragment. “It is a man. But not as we are—”

In the course of his education Athalaric had seen plenty of human skulls. The flat face and jaw of this skull were very human. But there was nothing human about the thick ridge of bone over the brow, or that small brain pan, so small he could have cupped it in one hand.

“I have longed to study such a relic,” Honorius said breathlessly. “Is it true, as Titus Lucretius Carus wrote, that the early men could endure any environment, though they lacked clothing and fire, that they traveled in bands like animals and slept on the ground or in thickets, that they could eat anything and rarely fall ill? Oh, you must come to Rome, sir. You must come to Gaul! For there is a cave there, a cave on the coast of the ocean, where I have seen, I have seen—”

But the Scythian, perhaps mindful of the gold that still lay out of his reach, was not listening. He held up the fragment like a trophy.

The Homo erectus skull, polished by a million years, gleamed in the sunlight.