Archaeologists excavating a Roman burial site at Spitalfields Market, London, found her decorated lead coffin and elaborate stone sarcophagus earlier this year, complete with skeleton, valuable funerary items and unique textiles.
Scientists from Oxford University extracted DNA from one of her molar teeth, which was well enough preserved to produce a genetic sequence that could be compared against a database of 11,000 present-day people from around the world.
"The only exact match was with someone who lives in Spain, which suggests that the Roman lady came from the Iberian peninsula," said Brian Sykes, professor of genetics at Oxford. Helen Chandler, the research scientist who carried out the work, said another possibility was that her mother was of Spanish origin because the type of DNA analysed is only inherited from the maternal line.
"It's possible that she was brought to the British Isles," Ms Chandler said. "It seems to fit in with the fact that the burial was fairly elaborate and she herself was quite important,"
Archaeologists from the Museum of London said it is rare to find a Roman stone sarcophagus lined with a lead coffin. They have also found three types of textiles, the first fabrics of Roman London. Bill White, a bone specialist at the Museum of London, said that a white, woven textile was under her pillow of bay leaves. Her shroud was woven with a golden thread and a red cloth adorned her coffin.
Dr White said it came as a surprise to find that she is probably of Spanish origin. "I thought she was more likely to be local, although we have known that people in Roman Britain were drawn from all over the empire."
A further bone test to analyse oxygen isotopes will confirm whether she had lived in a warmer climate, which would support her Spanish origin, Dr White said.
The woman was in her early 20s when she died of an unknown cause and had benefited from a healthy diet. At 5ft 5ins she was at least 2ins taller than the average woman at that time, Dr White said.
The Oxford scientists will analyse DNA from the skeletons in nearby graves to see whether she was buried near her relatives. Her grave was one of probably four buried close to the Roman Ermine Street, which was the main road north from London to Lincoln and York. The Romans often buried notable citizens near main roads so that people passing by could pay their respects.