Detailed Instructions: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Q: The kingdom grew to its largest extent under Mithridates VI, who conquered Colchis, Cappadocia, Paphlagonia, Bithynia, Lesser Armenia, the Bosporan Kingdom, the Greek colonies of the Tauric Chersonesos and for a brief time the Roman province of Asia. Mithridates VI, himself of mixed Persian and Greek ancestry, presented himself as the protector of the Greeks against the 'barbarians' of Rome styling himself as "King Mithridates Eupator Dionysus." and as the "great liberator". Mithridates also depicted himself with the anastole hairstyle of Alexander and used the symbolism of Herakles whom the Macedonian kings claimed descend from. After a long struggle with Rome in the Mithridatic wars, Pontus was defeated, part of it was incorporated into the Roman Republic as the province Bithynia and Pontus and the eastern half survived as a client kingdom.
A:
Who ruled when the Kingdom of Pontus' was at it's biggest?