Complex sentence: Woccon was one of two Catawban also known as Eastern Siouan languages of the eastern US, which together with the Western Siouan languages formed the Siouan language family.
Split into simpler sentences: Woccon was one of two Catawban also known as Eastern Siouan languages of the Eastern United States. Together with the Western Siouan languages, they formed the Siouan language family.