In Iron age times the Dengie area was part of the territory of the Trinovantes tribe who controlled an area similar to that of modern Essex.

Asheldham was an important Iron Age site with a Fort constructed with embankments and a settlement . Many Iron age items have been found in the immediate vicinity. The fort was probably built in the 5th century BC and still in good enough condition to be used as a fort by the Saxons several hundred years later.

 Site of Asheldham Camp

In the second century BC newcomers from France moved into the area to live at peace with the Trinovantes. The newcomers were known as the Belgae. They brought with them many new skills and customs including the introduction of gold coins and wheel made pottery. The Belgae improved the fort at Asheldham and established a settlement and a cemetery at Burnham on Crouch.

One of the main industries of the area was salt panning. Pits were dig on the foreshore near to the tidal limit and lined with clay. Sea water was allowed to flow into these pits and then the pits were closed to the sea. Nature was then allowed to work and evaporate the water leaving a deposit of concentrated brine. This brine was transferred into earthenware pots and dried off on fires. The accumulating earthenware and burnt clay was thrown to one side. After years of salt production these waste areas grew in size and are now called red hills due to the red colour of both fired clay and earthenware. The Dengie was an important area for salt production and red hills are still evident in several places. The trade continued until later roman times when improved techniques were introduced.

The invasion of Britain in AD 43 was fiercely resisted by the Trinovantes who were subject to harsh rule by the Romans  in comparison to more favourable treatment on neighbouring tribes who surrendered to the Romans.

The treatment was so harsh that in AD 60 the Trinovantes and the Iceni under Queen Boudicca revolted and destroyed the depleted 9th Roman Division before sacking Camulodunum ( Colchester). A Roman arm under British Governor Suetonious Paulinus defeated Boudicca in the late summer of AD60 with a massacre of the tribesmen.

The Roman Response was so severe that the Trinovantes name disappeared never to appear in the history books again.