The earliest evidence of sod houses dates back to the 9th century in the form of archaeological remains found in Ukraine. Sod houses were also used by the ancient Celts and Germans, and were common in parts of Europe and Asia until the 19th century. In North America, sod houses were used by settlers on the Great Plains in the 18th and 19th centuries, and were particularly popular in Nebraska, Kansas, and the Dakotas.