Prasutagus was king of a British Celtic tribe called the Iceni, who inhabited roughly what is now Norfolk, in the 1st century AD. His wife was Boudicca.
Prasutagus may have been installed as a pro-Roman ruler following the defeat of a rebellion of the Iceni in 47. As an ally of the Rome his tribe were allowed to remain nominally independent, and to ensure this Prasutagus named the Roman emperor as co-heir to his kingdom, along with his two daughters. When he died, in 60 or shortly before, the Romans ignored his will and took over, depriving the nobles of their lands and plundering the kingdom. Roman financiers called in their loans. Boudicca was flogged and their daughters raped. All this led to the revolt of the Iceni, under the leadership of Boudicca, in 60 or 61.
Prasutagus had, as was the custom, willed enough of his wealth to Rome that his tribe and the succession of leadership should not have required Roman interference.
However, after the death of Prasutagus an attempt was made by the Romans to make the Iceni a subject population.
This may indicate that the wealth of the Iceni was so vast to be considered worth the risks involved in setting aside Boudicca and the central family and to risk the wrath of the tribe to take its property and wealth in the name of Rome.