Thổ is a heterogeneous group; thus, local groups have distinct languages. However, all of Thổ languages belong to Vietic branch . Nguyễn Hữu Hoành (2009) classify Thổ languages into 5 groups base on their position in Vietic branch. •
Tày Poọng (
Poong or
Phong) and
Đan Lai (
Liha) - Lexicostatistical studies have found that Đan Lai and Poọng sharing 85% basic lexicon. Thus, Nguyễn (2009) identify them as dialects of a language. The speakers of this language reside mainly in
Con Cuông and
Tương Dương districts. It may also have close relation with
Hung language (Toum) in
Laos. •
Cuối, Nguyễn (2009) pointed out that Cuối is a distinct language with Vietnamese, Muong and Poọng-Đan Lai. This language have two dialects Cuối Chăm in Tân Hợp commune (
Tân Kỳ district) and Cuối Nếp (or Cuối Làng Lỡ) in
Thái Hòa town. Because of sharing 66% basic lexicon with Poọng, Nguyễn (2009) proposed to group Cuối with Tày Poọng-Đan Lai to form a subbranch in Vietic, parallel to Việt-Mường branch and Chứt branch. •
Mọn and Họ, The two dialects share 98% basic lexicon and have a closer relation with Mường languages than Cuối and Poọng. They share 77%, 79% and 71% core lexicon with Mường Bi language, Mường Ống language and Nghệ An dialect of Vietnamese, respectively. Especially, Mọn and Họ are lexical closest with a Mường language in Như Xuân district (84%). Therefore, Nguyễn (2009) group them into a single language in Việt-Mường branch which have a closer relation with Mường languages. Maspéro (1912) named this language as
Southern Mường language •
Kẹo share 99% lexicon with Nghệ An dialect of Vietnamese. Thus, Nguyễn(2009) classified Kẹo as a dialect of Vietnamese or even a sub-dialect of Nghệ An dialect •
Thổ Lâm La and Thổ Như Xuân share respectively 94% and 95% basic lexicon with Nghệ An dialect. However, Nguyễn (2009) argued that two Thổ languages experienced a different phonological innovation with Vietnamese. Thus, he placed it into a grey area between being dialects of Vietnamese or being member languages of Viet-Muong branch (
Nguồn has a similar status). ==Distribution==