Answer: History
They are all historians: Gibbon was an 18th century Englishman specialising in the Roman Empire; Michael King was a 20th century New Zealander specialising in Maori history; Simon Schama is a 20th century Englishman specialising in art history, Dutch history, and French history; Josephus was a first-century Romano-Jewish scholar, historian and hagiographer; Herodotus was a 5th century BCE Greek historian (known as the earliest).