Sure enough, the Zapotecs were reaching for a greater carrying capacity than would ever be possible in a dugout canoe made from a single tree. At first it consisted of wide decks straddling the sides of the canoe and reaching beyond, but this became unwieldy, making the boat too likely to tip. A better solution was to shape a second tree into a vertical extension of the sides of the canoe, lashed to the hull by the use of holes bored into the sides. To make it watertight they smeared the surfaces with sap before they put them together, making a glue-like bond when it was lashed tight.

"Clever," said Kemal.

"It doubles the carrying capacity of the ships. But it slows them down, too -- they tend to wallow in the water. What matters, though, is that they've learned to join wood and make it watertight. Single-tree construction is over. It's just a matter of time before the original one-tree canoe becomes the keel, and planks are used to make a much wider, shallower hull."

"A matter of time," said Kemal. "But you don't actually see any being made."

"What they lack is adequate tools," said Hunahpu. "When Tlaxcala takes over the Aztec empire, the bronze of the Tarascans will come to the Zapotecs, and they'll be able to make boards more efficiently and with more reliably smooth surfaces. The point is that when they make any innovation, it spreads quickly. And the Zapotecs are also under pressure from the Aztecs. They have to find sources of supply because the Mexican armies have forced them from their fields. In this swampy land, farming is always precarious. So look where they're sailing."

He showed them the clumsy, wallowing Zapotec ships carrying large cargos from Veracruz and the Yucatan. "Slow as these ships are, they carry enough cargo on each trip to make the voyages profitable. They're far enough up the coast of Veracruz now to be in contact with the Tlaxcalans; and the Tarascans. And here." Again the view changed. "This is the island of Hispaniola. And look who's coming to visit."

Three Zapotecan ships slipped up to the shore.

"Unfortunately," said Hunahpu, "Columbus was already there."

"But if he hadn't been there," said Diko, "it could have extended the reach of a Tlaxcalan empire out to the islands."

"Exactly," said Hunahpu.

"There was already extensive contact between Mesoamerica and the Caribbean islands," said Kemal.

"Of course," said Hunahpu. "The Taino culture was actually an overlay by earlier raiders from the Yucatan. They brought the ball court with them, for instance, and established themselves as the ruling class. But they adopted the Arawak language and soon forgot their origins, and they certainly did not establish regular trade routes. Why should they? The boats didn't carry enough to make trade profitable. Only raiding was worth the effort, and the Caribs were the raiders, not the Taino, and since they came out of the southeastern Caribbean, Mesoamerica was even further out of reach. The Taino knew about Mesoamerica as a fabled land of gold and wealth and mighty gods -- that's what they meant when they kept telling Columbus that the land of gold was to the west -- but they had no regular contact. These Zapotecan ships would have changed all that. Especially as the ships got bigger and better. It would have been the beginning of a sailing tradition that would have led to ships that could cross the Atlantic.

"Very speculative," said Kemal.

"Forgive me," said Diko, "but isn't that what your entire project is? Speculation?"

Kemal glowered at her.

"What matters," said Hunahpu, anxious not to antagonize Kemal, "is not the details. What matters is that the Zapotecs were innovating, they reached the islands with ships that could carry larger cargos, and they were also a familiar sight to the Tlaxcalans along the coast of Veracruz. It's unthinkable that the Tlaxcalans would not have seized upon this new technology just as they reached for the bronze-working of the Tarascans. It was an age of invention and innovation in Mesoamerica, and the only barrier was the ultraconservative Mexica leadership. That was doomed -- everyone knows it -- and it seems obvious to me from this evidence that the Tlaxcalans would have become the successor empire, and as the Persians far outstripped the empire of the Chaldeans, so also the innovative, politically sophisticated Tlaxcalan empire would have outreached the empire of the Mexica."

"You've made that case very well," said Kemal.

Hunahpu almost allowed himself a sigh of relief.

"But you have claimed much more than that, haven't you? And for those claims you have no evidence."

"Columbus's discovery erased all the other evidence," said Hunahpu. "But then, the Intervention also erased Columbus's crusade to the east. I think we're on equal ground here."

"Equally shaky," said Kemal.

"Kemal is heading the speculative aspects of our research," said Tagiri, "precisely because he is profoundly skeptical about it. He doesn't believe an accurate reconstruction is possible."

That thought had never occurred to Hunahpu -- that Kemal was predisposed to reject all speculations. He had assumed that his only task was to bring Kemal to consider another possible scenario, not that he had to persuade him that it was possible to construct a scenario at all.

Diko seemed to sense his consternation. "Hunahpu," she said, "let's leave aside the issue of what can and can't be proved. You must have developed the rest of the story in your mind. Let's regard it as likely that Tlaxcala has conquered and unified the whole of the old Mexica empire, and that now it's running smoothly with Zapotecan ships trading far and wide and Tarascan bronzeworkers making weapons and tools for them. What then?"

Her guidance helped him recover his confidence. Trying to convince the great Kemal against his will was too much to contemplate; talking about ideas he could do. "First, you have to remember," said Hunahpu, "that there was one problem of the Mexica that the Tlaxcalans had not overcome. As with the Mexica, the Tlaxcalan practice of wholesale sacrifice to their bloodthirsty god would have drained away the manpower they needed to feed their population."

"So? How do you resolve it?" asked Kemal. "You wouldn't have come here if you didn't have an answer."

"I have a possibility, anyway. There's nothing in the evidence, because Tlaxcala hadn't had to govern a real empire yet. But they couldn't have succeeded if they made the same mistake the Mexica made, slaughtering the able-bodied men of their subject populations. So here's how I think they would have solved it. There is a hint of a doctrine among the priestly class that their warrior god Camaxtli becomes especially thirsty for blood after he has exerted himself to give Tlaxcala a victory. The existence of this idea makes it possible for the Tlaxcalans to evolve the practice of only offering huge mass sacrifices after a military victory, because that's the only time that Camaxtli is especially in need of blood. So if a city or nation or tribe willingly allies itself with Tlaxcala, submits to their overlordship, and allows the Tlaxcalan bureaucracy to administer their affairs, then instead of being sacrificed, their men are left to work the fields. Perhaps, if they prove to be trustworthy, they can even join the Tlaxcalan army, or fight alongside it. The mass sacrifices are only performed using captives from armies that resist. Aside from that, peacetime sacrifices in the Tlaxcalan empire would stay at a tolerable level -- the way they were before the Mexica arose to form the Aztec empire in the first place."

"It gives the surrounding nations a reward for surrendering," said Hassan. "And a reason not to rebel."

"Just the way so much of the Roman Empire didn't have to be conquered," said Hunahpu. "The Romans seemed so irresistible that kings of neighboring countries would make the Roman senate the heir to their thrones, so that they could live as sovereigns until they died, and then their kingdoms would pass peacefully into the Roman system. It's the cheapest way to build an empire, and the best, since there's no war damage to the newly acquired lands."