As with most towns and villages in England, Yarmouth's first definitive documentation is to be found in the Domesday Book which was commissioned by William I (The Conqueror) to evaluate the value of his kingdom.
Great Yarmouth became an important town in the middle ages owing to it's geographical location, being on the North Sea coast where two rivers reach the sea. At the time the River Bure reached the North Sea somewhere between Caister-on-Sea and Great Yarmouth. The River Yare reached the sea, well to the south of its present position as the sand bar on which modern Great Yarmouth is located, stretched as far as Lowestoft. The mouths, of both these rivers had access to Great Yarmouth quays on the land side of the sandbank.
The river mouth of the River Bure was the more important until it was silted up in the 14th century. Around the same time the same fate befell the mouth of the River Yare but it was decided that this passageway to the North Sea should be maintained. A considerable amount of trade with the Netherlands, Germany, France and the Baltic was carried out from Great Yarmouth. Herrings were the most important commodity exported throughout the medieval period but by the 14th century wool and worsteds from Norwich had grown to become equal in importance.