Berber languages suggests that the C-Group population — which, along with the Kerma culture, inhabited the Nile valley immediately before the arrival of the first Nubian speakers — spoke Afro-Asiatic languages. Roger Blench (2018) suggests that Proto-Berber speakers had spread from the Nile River valley to North Africa 4,000-5,000 years ago due to the spread of pastoralism, and experienced intense language leveling about 2,000 years ago as the Roman Empire was expanding in North Africa. Hence, although Berber had split off from Afroasiatic several thousand years ago, Proto-Berber itself can only be reconstructed to a period as late as 200 A.D. Blench
Proto-Berber language are the only Berber languages to preserve Proto-Berber *β as β; elsewhere in Berber it becomes "h" or disappears. The Proto-Berber consonantal system reconstructed by Allati (cf. Allati, 2002, 2011) is based on remains from the ancient stages of this language preserved in the ancient toponymical stratas, in Libyan inscriptions and in the modern Berber varieties. It had stops b, t, d, k, g; fricative s; nasal n and liquids l, r. The stops of the phonological system have evolved since the proto-Berber stage into variants from which other consonants have been progressively formed (Allati, 2002, 2011). Karl G. Prasse