Diyari (/ˈdiːjɑːri/) or Dieri (/ˈdɪəri/) is an Australian Aboriginal language spoken by the Diyari people in the far north of South Australia, to the east of Lake Eyre. It was studied by German Lutheran missionaries who translated Christian works into the language in the late 19th and early 20th centuries, so that it developed an extensive written form. Only a few fluent speakers of Diyari remained by the early 21st century, but a dictionary and grammar of the language was produced by linguist Peter K. Austin, and there is a project under way to teach it in schools.