Simplify the following text for a Grade 8 native English-speaking person.
Original: It was visited by Hanno the Carthaginian around 450 BC at his navigation from Carthage through the pillars of Herakles to Theon Ochema ( Mount Cameroon ) in the Gulf of Guinea .
Simplified: Hanno the Carthaginian went to the river in about 450 BC when he was going from Carthage to Mount Cameroon in the Gulf of Guinea .