Australian researcher Jaye Pont from the Museum of Ancient Cultures at Sydney's Macquarie University says people who lived in Pompeii bought their pottery locally and didn't import it.
Pont said the find could "make waves" among archaeologists looking at trade in the Mediterranean.
And she said researchers may have to rethink shelves of museum pottery once thought to be from the eastern Roman Empire.
Pont looked at a particular type of red pottery from a city block in Pompeii that had been buried beneath rubble from the Mount Vesuvius eruption in 79 AD.
The city block had been inhabited since the 4th century BC. And an international group of researchers, known as the Anglo American Project in Pompeii, found thousands of samples of red slip pottery there.
This type of pottery was made by dipping a partly dried plate or bowl into a water-and-clay mix called slip. The vessel would then be fired to give it a red, shiny colour.
Previously, archaeologists had thought much of this pottery was imported from the eastern Roman Empire based at Constantinople, with the rest coming from northern Italy and Gallic France.
But Pont, who is doing her PhD on the pottery and is a potter, has found that all the "imported" pottery was local.
Who did Pompeii trade with?
Pont said her research would "turn upside down" old notions of commerce and trade between Pompeii and the eastern Roman Empire.
Inhabitants of Pompeii and other areas such as northern Africa, where the pottery is also found, were thought to have traded extensively with the eastern Roman Empire.
"The fact that I have not found one piece that has been imported I think will have quite large implications for trade and commerce in that area," Pont told ABC Science Online.
The flecks, which contained the mineral leucite, were identical in composition and unique to the Bay of Naples region, where Mount Vesuvius is found.
Most scientific analysis has been done chemically but not through thin section analysis, Pont said. But she said thin section analysis was "very clear cut": either the pottery is from the area or it isn't.
Pont said archaeologists made the mistake of thinking the pottery was imported because there was a lot of variation in the colour and quality of the local pottery compared to the pottery from northern Italy.
And archaeologists had based their classification of the pottery on these variations, she said.
"As a potter, perhaps I could see things archaeologists couldn't," said Pont. "In general archaeologists don't understand how [pottery] is made. They can't identify manufacturing techniques within a vessel."
She said archaeologists rely a lot on colour to differentiate vessels.
"I could understand that even in one kiln, what you get at the top and at the bottom of the kiln can be very different in colour."
Pottery is also classified by form, yet pottery "isn't an exact science", said Pont.
"But whole assemblages have been grouped by rim shape ... When I looked at [the pottery] I couldn't see the difference. It turns out there wasn't a difference."
She said the red slip pottery, known as terra sigillata, was also differentiated on the condition of the slip that coloured the vessel.
"It is read as gospel that eastern sigillata didn't have a slip that worked well. But if you have a potter with greasy fingers, that slip will peel off," she said.
Pont said although she has only excavated one city block, the fact that she was yet to find one piece that has been imported could make archaeologists reconsider shelves of museum pottery.