Today, the Silk Road goes to sea. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

The storied Silk Road is truly the stuff of ancient romance. It was a route that reached from China to ports on the eastern end of the Mediterranean. Camel caravans of tea, silk, gems, and spices, moving slowly through Tibet, Siberia, Samarkand, and Baghdad -- trying to evade bandits and other dangers along the way. But the last leg of the Silk Road was usually a long sea voyage on the Mediterranean -- often as far as Rome.

Ocean-going merchant ships were already well developed. Typically, they were large, slow-moving, square-rigged vessels. They could be as long as 180 feet and carry as much as a thousand tons of goods. And there hangs our story:

For archaeologists have now found another equally important route for oriental goods that was almost entirely by sea. Science writer John Noble Wilford tells of excavations on the Red Sea in southern Egypt over a thousand kilometers from Cairo or Alexandria.

These ancient ruined cities reveal a thriving ocean trade from all the way across the Indian Ocean -- from present-day Pakistan, Calcutta, and even as far as Canton and Java. The cities were becoming major seaports two hundred years before the birth of Christ. A stretch of southern Egyptian coast turns out to've been a major way station in a vast oceanic version of the old Silk Road. Small wonder that Roman imports grew so large that Emperor Tiberius had to worry about Rome's balance of trade.

The ships came in around the Arabian Peninsula to these ports halfway up the Red Sea. But why did they stop there? The reason is that the coast of Egypt is dangerously rocky, and it's constantly raked by north winds. It was much safer to unload goods in the south without trying to sail the Egyptian coast. So goods were unloaded and taken two or three hundred miles by caravan to the Nile River. Then they traveled by boat to the port of Alexandria.

Evidence of many kinds testifies to how heavy the traffic through the Indian Ocean became. These ancient ruins have yielded documents written in at least eleven languages. Archaeologists are finding casual remains of sapphire, peppercorns, and beads from the Orient. And there is evidence of outbound products -- like wines and Egyptian glass.

They also find that some oriental ships were made of valuable teak wood. They carried one rich load of goods from the Orient. Then they were taken apart to be made into expensive furniture.

All this ended in the late days of the Roman Empire. The ports silted over, and the cities died. Another six hundred years, and Marco Polo would go to China to renew Europe's awareness of the rich culture far to the East.

And only now do we discover just what a vast global trade was routinely being carried on -- well over a millennium before Marco Polo.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

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Wilford, J. N., Under Centuries of Sand, a Trading Hub. The New York Times, SCIENCE TIMES, Tuesday, July 9, 2002, pp. D1, D9.

Representation of an Egyptian wall painting -- the earliest known image of a boat
(from The Story of the Ship, 1919)

An Egyptian boat model, Museum of Fine Arts, Houston.