Koryo-mar

Koryo-mar (Korean: 고려말; Russian: Корё мар) is a dialect of Korean spoken by Koryo-saram, ethnic Koreans who live in the countries of the former Soviet Union. It is descended from the Hamgyŏng dialect and multiple other varieties of Northeastern Korean. Koryo-mar is often reported as difficult to understand by speakers of standard Korean; this may be compounded by the fact that the majority of Koryo-saram today use Russian and not Korean as their first language.

According to German Kim, Koryo-mar is not widely used in the media and is not taught in schools. Thus it can be classified as endangered.