Little is known about the archaeology of Saudi Arabia, as the government has historically forbid aerial photographs of the landscape and religious sensitivities have made access tricky. But Google Earth is changing that. Satellite images available via the Web-based 3-D map program show that large portions of the country hold a wealth of archaeological remains that predate Islam and may be several thousand years old.

Researchers recently discovered nearly 2,000 tombs by peering through one high-resolution "window" at a rocky lava field east of the city of Jeddah — all without having to set foot in the Saudi desert.

Judging by the sheer number of stone ruins identified in Saudi Arabia, as well as in other research in Jordan, there may well be a million such sites scattered throughout the Arabian Peninsula, said David Kennedy, an archaeologist at the University of Western Australia who led the study.

Eye in the sky

Kennedy has spent the past 35 years surveying Jordanian archaeological sites, mainly from aircraft — a technique that archaeologists have relied on for decades to identify and map sites not readily visible from the ground. He found plenty of sites near the Saudi border, but wondered what was on the other side. The Saudi government had commissioneda broad archaeological survey in the 1970s and 1980s that revealed about 1,800 tombs and other sites throughout the country, but the government all but prohibited the use of aerial photography even to its own surveyors.

Juris Zarins, an archaeologist who worked in Saudi Arabia for 15 years and led parts of the national survey, suggests religious sensitivities play a role in the government’s limitations on archaeology . "They don’t want people fooling around with prehistory because it contradicts the Koran — any more than fundamentalist Christians want anyone to say anything is older than six thousand years," Zarins told LiveScience.

Since satellite imagery has become widely available in the last decade, and particularly since Google Earth launched in 2005, archaeologists have used it to scan for ruins over large landscapes around the globe. About two years ago, a few sharp windows on Saudi Arabia opened up, and Kennedy got his first peek at the ground.

"I was able to actually see across the border, courtesy of Google," he said, and what he saw was "marvelous" — thousands of sites in just the handful of available windows.

Window on the desert

Kennedy and a Saudi collaborator started with a preliminary study of a small area 250 miles(400 kilometers) north of the Jeddah site. There they spotted hundreds of large stone structures called kites, which scientists think were used for trapping and corralling animals.

For the present study, published online Jan. 28 in the Journal of Archaeological Science, Kennedy and a colleague, M.C. Bishop, took a more methodical look at a 480-square-mile window near Jeddah. They located 1,977 structures built of basalt stone from the surrounding lava field. The most numerous are cairns — circular mounds similar to collapsed tombs found in Jordan and Yemen — and "pendants," which are cairns from which processions of small stone piles march as far as 3 miles off into the desert.

Some of the funeral monuments stand alone, others were built on top of one another; some are aligned, others are scattered willy-nilly across the landscape. Most of them were probably looted long ago, Kennedy said. A few less distinctively shaped ruins could be the remains of seasonal living quarters.

Kennedy sent the coordinates of a couple of sites to a friend living near Jeddah, who forayed into the desert with a GPS to photograph them. Where the satellite images clearly show a cairn and its pendant, photographs show a "rather uninspiring sea of boulders" that would be "a nightmare" to attempt to locate or map from the ground, Kennedy said.