A Norwegian-Syrian team of archaeologists has solved one of the great puzzles of the Roman Empire: why was the vibrant city of Palmyra located in the middle of the Syrian Desert?

In Roman times, Palmyra was the most important point along the trade route linking the east and west, reaching a population of 100,000 inhabitants. But its history has always been shrouded in mystery: what was a city that size doing in the middle of the desert? How could so many people live in such an inhospitable place nearly 2,000 years ago?

Norwegian researchers collaborated with colleagues from Syria for four years to find answers.

“These findings provide a wealth of new insight into Palmyra’s history,” said Jørgen Christian Meyer, a professor at the University of Bergen and manager of the project funded by the Research Council of Norway.

The Norwegian archaeologists approached the problem from a novel angle – instead of examining the city itself, they studied an enormous expanse of land just to the north. Along with their Syrian colleagues from the Palmyra Museum and aided by satellite photos, they catalogued a large number of ancient remains visible on the Earth’s surface.

“In this way, we were able to form a more complete picture of what occurred within the larger area,” Prof Meyer said.

The team detected a number of forgotten villages from ancient Roman times. But what finally solved the riddle of Palmyra was the discovery of the water reservoirs these villages had utilized. The researchers came to realize that what they were studying was not a desert, but rather an arid steppe, with underground grass roots that keep rain from sinking into the soil. Rainwater collects in intermittent creeks and rivers called wadi by the Arabs.

The team also gathered evidence that residents of ancient Palmyra and the nearby villages collected the rainwater using dams and cisterns. This gave the surrounding villages water for crops and enabled them to provide the city with food; the collection system ensured a stable supply of agricultural products and averted catastrophe during droughts.

Local farmers also cooperated with Bedouin tribes, who drove their flocks of sheep and goats into the area to graze during the hot season, fertilizing the farmers’ fields in the process.

Palmyra’s location also had a political foundation. Important east-west trade routes, including along the Euphrates River to the north, were not under the control of the Romans to the west or the Persians to the east. Local lords and chieftains demanded high fees for passage.

This practice of extortion translated into a tremendous opportunity for the Palmyrians, they joined forces with the Bedouins to provide security, beasts of burden and guides through the desert.

“Tradesmen from Palmyra made the most of the city’s unique location to build up a comprehensive trade network. This explains much of the city’s prosperity,” Prof Meyer concluded.