Atakapa
Atakapa, called Ishakkoy or Yukhiti Koy by its speakers, is a language isolate of the Gulf Coast, spoken along the marshes and river mouths of southwestern Louisiana and southeastern Texas by the Ishak people. The Choctaw named them Atakapa, meaning man-eater, for their ritual cannibalism.
The first Europeans to meet them were survivors of the failed Narvaez expedition cast ashore in 1528, whose treasurer Cabeza de Vaca wrote the earliest account of the coastal bands. By the seventeenth century the Atakapa traded with the Caddo, Chitimacha and Karankawa, and French explorers under La Salle entered their territory in 1685.
The language existed in eastern and western dialects and was never written by its speakers; a French officer took down a vocabulary at Galveston Bay in 1721, and a fuller French-Atakapa glossary was compiled in 1802.