Excited chatter filled the classroom as the lesson began. Every desk had a paper nameplate on it with the occupant’s name written in the Korean alphabet, called Hangul. Soon, the students were following their instructor’s lead and etching the distinctive circles and lines of the script in their notebooks.

But these fourth graders were not studying the Korean language. They were using Hangul to write and learn theirs: Cia-Cia, an indigenous language that has no script. It has survived orally for centuries in Indonesia, and is now spoken by about 93,000 people in the Cia-Cia tribe on Buton Island, southeast of the peninsula of Sulawesi Island in Indonesia’s vast archipelago.

“Say, ‘ph.’ Hold a piece of paper in front of your mouth and make sure the paper moves when you pronounce it,” Deuk-young Jung, who has been teaching the alphabet here for more than a decade, told his 40 or so students at Hendea Elementary School, south of the town of Baubau.

Indonesia is home to myriad tribes and cultures, and to more than 700 native languages. It is the most linguistically diverse nation in the world after neighboring Papua New Guinea. On Buton Island alone, there are a handful of local languages and almost two dozen dialects. However, most of them are at risk of disappearing because they do not have a script.

“Language is the wealth of a community, a legacy,” said Amirul Tamim, a former mayor of Baubau who was been instrumental in efforts to preserve the Cia-Cia language. “Language shows the civilization of a tribe, and a language without its own alphabet loses its authenticity.”