The word might derive from the Welsh term echen, meaning origin or source. D. F. Allen examined coins from the first century AD that spell the tribe's name as ECEN. Sir Thomas Browne proposed in 1658 that Iken was an ancient name for the River Ouse.
Boudica led the Iceni and neighboring Trinovantes in a large-scale revolt from 60 to 61. King Prasutagus died around AD 60 after Roman authorities seized his entire estate despite his attempt to bequeath his kingdom jointly to the Emperor and his daughters. Gaius Suetonius Paulinus commanded the legions that crushed the rebellion near Watling Street.
Venta Icenorum became the capital of the Iceni following the rebellion. This settlement sat eight kilometers south of present-day Norwich near Caistor St Edmund. The city of Norwich arose later from the ruins of Venta itself.
Tacitus recorded that eighty thousand Romans and allies perished during these events. Boudica wore a large golden necklace and a thick mantle fastened with a brooch while her forces sacked Camulodunum, Londinium, and Verulamium before facing defeat.
The Iceni began producing coins around 10 BC using a distinctive Gallo-Belgic design. These artifacts are the only coin-producing group to use their tribal name on currency. Antedios appears as the earliest personal name on coins about 10 BC.