Because Swaffham market is not a charter market we only know that it existed before 1216 because of a failed attempt to have it abolished. It was damaging the market at Dunham. The market was confirmed in 1253 when a weekly market and 3 fairs a year were permitted by Henry III.
In medieval times cows and sheep were sold at the Saturday market and there is still a Saturday market where you can purchase all sorts of things including clothes, gadgets and machinery.
Every Saturday a market auction is held on the Stones outside and around the Greyhound.