John Noble Wilford. "Ruins in Yemeni Desert Mark Route of Frankincense Trade", New York Times, Tuesday, January 28, 1997, B9-B10.

Exploring the remote back country of Yemen, over hills and through wadis, a party of archeologists this month came upon ruins and monuments from the time when frankincense and myrrh were among the world's most coveted commodities. Here were lithic memories of a happily prosperous epoch in the land known to the Romans as Arabia Felix.

In the 10th century B.C., the biblical Queen of Sheba is supposed to have ruled in golden splendor over this land on the southern rim of the Arabian peninsula. For several hundred years before and after the birth of Christ, it was a major emporium of the ancient world. SPices and textiles arrived by ship from India, silk from China and gold and ostrich feathers from Ethiopia. These goods were then packed off by camel caravan to Egypt and Persia, to Palmyra in Syria and, often as not, on to Rome.

Nothing in the shipments was more prized than the two locally grown gum-resin products, frankincense and myrrh. Myrrh was an ingredient of cosmetics and perfumes, a social kindness in cultures unaccustomed to daily bathing, and was applied medicinally in poultices and ointments. Egyptians used frankincense in embalming, and the pharaohs believed that burning it allowed them to commune with the gods. Nearly everywhere it was part of religious ceremonies and cremations. At the funeral of Nero's wife, Pliny the Elder wrote, an entire year's harvest of frankincense was burned.

The central role of Arabia Felix (roughtly, Happy Arabia) in the ancient incense trade has long been known in outline from historical accounts. But until now, archeologists have had few opportunities to investigate the incense-growing regions of this ancient land, which included present-day Yemen and part of Oman.

Five years ago, a team of American and British explorers found in southern Oman the ruins of two frankincense trading centers that had appeared on the maps of Claudius Ptolemy, the Alexandrian geographer of the second century A.D. One of them is possibly the legendary lost city of Ubar. The team's more recent excavations uncovered a previously unknown pattern of sites associated with frankincense over a period from 5000 B.C. through the Roman Empire.

A new expedition by some of the same explorers, organized by George R. Hedges, a Los Angeles lawyer with a background in archeology, returned last week from an extensive reconnaissance in trucks across the border into the Mahra region of Yemen. Covering some 2,000 miles in three weeks, the team found the ruins of two limestone fortresses, which are similar in design and construction to those in the incense region of Oman. They also came upon distinctive stone monuments, called triliths, that appeared to mark caravan routes.

"No archeologists had ever been in this area," said Dr. Juris Zarins of Southwest Missouri State University in Springfield, who specializes in Arabian archeology.

At several settlements, Dr. Zarins collected shards of pottery in a style corresponding to that found at frankincense sites in Oman. Mixed with the local pottery were pieces of red- painted ceramics from ancient Persia. This, he said, was further evidence that "a vast amount of trade in incense in Roman times was really under the thumb of the Persians."

The Persian influence suggests a possible link between southern Arabia and the Magi who brought gifts of frankincense and myrrh, as well as gold, to the Christ child. Some biblical scholars think the Three Wise Men came from Persia. Or perhaps they were from Arabia Felix itself. In any event, their gifts probably originated there, and the fact that frankincense and myrrh were accorded a place with gold in the biblical account is no doubt a measure of the value of the substances to ancient people.

Others familiar with the history and archeology of the ancient frankincense trade said the new findings appeared to contain no surprises. But for the expedition to be allowed in eastern Yemen, they said, augured well more more intensive explorations in the future. Mr. Hedges is planning another expedition there in December to begin methodical excavations.

"What is perhaps most remarkable," Mr Hedges said in an interview, "is that in this day and age a region that held great significance and fascination for ancient people in as far-flung places as Rome, Greece and Persia is ony now revealing itself, and only with great effort."

IN addition to Mr. Hedges and Dr. Zarins, the princpal members of the team were Dr. Ronald G. Blom, a geologist and specialist in space remote-sensing technology at the Jet Propulsion Laboratory in Pasadena, Calif.; Dr. Geraldina Santini, an archeologist with the Oriental Institute of the University of Naples, and Nora Marinez, a botanist at the Huntington Botanical Gardens in San Marino, Calif. The expedition was conducted under the auspices of the American Institute for Yemeni Studies, a consortium of American universities based in Sana, the capital of Yemen. One of the financial backers was the J. M. Kaplan Fund of New York.

The Mahra region of eastern Yemen had until recently been off-limits for Westerners. First, it had been controlled by the People's Republic of Yemen until 1987. Then civil war, onw over, made it unsafe for anyone, much less foreign archeologists.

As in the earlier explorations in the adjacent Dhofar region of Oman, the expedition ranged form the coast of the GUlf of Aden over rugged hills and across sparsely populated arid lands to the fringes of the Rub al Khali, the forbidding Empty Quarter that stretches over much of the Arabian interior. The team relied on maps by Ptolemy and photographs from Landsat spacecraft.

"We used Landsat pictures to identify sites we wanted to look at and also just to navigate from place to place," Dr. Blom said. "The regular maps of that part of the world are not the best."

But often the expedition was directed to its discoveries by people they chanced to meet. A tip from a police colonel in Sayhut, on the coast at the start of the reconnaissance, led to the first impressive find.

On a hill four miles out of town, they saw what they are calling the Fortress of Gaydah al Kabir. It took only a cursory examination for Dr. Zarins to recognize that the site was almost identical to the trading centers found five years earlier at Shisur and Ain Humran, in southern Oman where Ptolemy said the "people of Ubar" lived. Within thick stone walls stood a central building, like a castle, and at the base of the hill were the traces of an ancient settlement and agricultural fields.

Pliny the Elder, in the first century A.D., reported that the frankincense region could be found by traveling a route from Shabwa, an ancient city in Arabia Felix that still exists, that was marked at stages by eight small fortresses or rest stations. The sites in Oman are presumably the last fortresses in the route, and now the archeologists think they have found two of the intermediate fortresses.

They came upon the second fort on a plateau overlooking the Minar wadi, a valley with a dry stream bed. The Fortress of Minar, their name for the ruins, resembled in all important respects the other known sites. And pottery thee dated the fort to the heyday of the frankincense trade, 200 B.C. to about A.D. 300.

Between the forts and elsewhere in the region, the archeologists discovered more than 30 triliths. These lines of standing stones, three to a group and about three to five feet high, had previously been recognized as identifiable features of the trade routes. Studying the pattern of triliths on their course, Mr. Hedges said, the expedition confirmed that these are indeed route markers and that they probably convey distances, locations of water and directions.

At this time, the expedition was traveling deep into what the Ptolemy map labels Myrrifera Regio, roughly translated as Myrrh Country. "And so it is," Mr. Hedges said. "Along the track we saw large groves of myrrh trees, some over 10 feet high."

Myrrh is a clear resin secreted by Commiphora myrrha, trees with thick trunks and spiny branches with little green leaves. The resin, usually tapped twice a year, soon hardens to become a reddish or yellowish-brown gum. On the way to his crucifixion, according to the Gospel of St. Mark, Jesus declined the offer of a drink of wine mixed with myrrh, something that might have had a mild narcotic effect.

The Expedition found few signs of frankincense in the region today; its principal source was probably not far away in the Qara Mountains along the coast of Oman, where the monsoons of the Indian Ocean provide more moisture. Frankincense is the aromatic resin from bushy trees of the genus Boswellia, named for James Boswell, the biographer of Dr. Samuel Johnson.

At a Bedouin village, where they camped in the courtyard of a mosque, the archeologists were told of a mysterious ancient site nearby. What they saw was a field of megaliths, 19 stones about 6 feet tall, arranged in a circle with a circumference of about 250 feet. Beyond the ring lay ruins of small structures and a site where Late Stone Age people appeared to have made flint tools and weapons.

Here were traces of a time long before Arabia Felix was a thriving hub of ancient trade. But archeologists are at a loss to explain the purpose of the megaliths, any more than they can be sure of the meaning of Stonehenge in England. "When archeologists can find no sign that people lived or died at a place," Dr. Zarins said, "they are usually reduced to saying that it must have some ceremonial purpose."

The decline of the civilization of Arabia Felix started in the fourth century A.D. For one thing, the Romans had found out that most of the luxury goods, aside from incense, were actually coming from the east; as they and others learned to sail the monsoon winds, they could bypass these Arabian middlemen.

Dr. Gus W. Van Beck, a former curator of Old World archeology at the Smithsonian Institution, writing in 1969, said the collapse of the frankincense market was the most important reason for the decline. When Constantine proclaimed Christianity the state religion of the Roman Empire in 323, simple burials replaced cremation and the elimination of funeral pyres cut heavily into the demand for frankincense.