Tumak language

Tumak, also known as Toumak, Tumag, Tummok, Sara Toumak, Tumac, and Dije, is an Afro-Asiatic language spoken in the southwestern Chadian prefectures of Moyen-Chari and Koumra. Motun (Mod) and Tumak dialects have a lexical similarity of only 70%; Blench (2006) lists Tumak, Motun, and Mawer as separate languages. Most Motun speakers use some Sara.

The "Gulei" listed in Greenberg might be a dialect of Tumak.

Phonology
Tumak also has two tones; high and low.