Complex sentence: By 1650, it had become the site of a town formed by immigrants from the interior who spoke the Douala language.and during the eighteenth century it was center of the transatlantic slave trade.
Split into simpler sentences: By 1650, it had become the site of a town formed by immigrants from the interior who spoke the Douala language. And during the 18th century it was center of the transatlantic slave trade.