Siouan languages
Siouan or Siouan–Catawban is a language family of North America that is located primarily in the Great Plains, Ohio and Mississippi valleys and southeastern North America with a few other languages in the east.
Siwai language
Motuna or Siwai, also known as "Telei, Rugara", is a Papuan language of Bougainville Province, Papua New Guinea. The current number of speakers is difficult to estimate since the latest figure (6,000 + 600) is from the 1970 census.