Where does the name of the UK county 'Essex' originate from?

Context: The name Essex originates in the Anglo-Saxon period of the Early Middle Ages and has its root in the Anglo-Saxon name Ēastseaxe, the eastern kingdom of the Saxons who had come from the continent and settled in Britain. Excavations at Mucking have demonstrated the presence of Anglo-Saxon settlers in the early fifth century, however the way in which these settlers became ascendent in the territory of the Trinovantes is not known. Studies suggest a pattern of typically peaceful co-existence, with the structure of the Romano-British landscape being maintained, and with the Saxon settlers believed to have been in the minority.

Answer: The name Essex originates in the Anglo-Saxon period of the Early Middle Ages and has its root in the Anglo-Saxon (Old English) name Ēastseaxe ("East Saxons").