Wiktionary:About Proto-Abkhaz-Abaza

Proto-Abkhaz-Abaza is the ancestor of Abkhaz-Abaza languages. It is a descendant of Northwest Caucasian. No written records of Proto-Abkhaz-Abaza exist, but the words and grammar of the language have been reconstructed by historical linguists. The Abkhaz-Abaza languages are common in the Western and Central Caucasus, on both sides of the Main Caucasian ridge. After the invasion of the Tatar-Mongols in the XIII century and the hordes of Tamerlane in the XIV centuries, groups of Abaza began to move to the liberated lands from the south to the north from the Caucasian ridge — first, tapanta (“inhabitants of the plain”), and then ashkharywa (“highlanders”), who occupied part of the territory of modern Karachay-Cherkess.

Vowel inventory
Proto-Abkhaz-Abaza had a simple vowel system, with two qualities:

Accentuation system
The Proto-Abkhaz-Abaza accent system depends on a set of phonologically contrastive accentual specifications. In the data considered here, every syllable of every morpheme is lexically specified as either dominant or recessive (Dybo 1977, Dybo 1978, Spruit 1986, Dybo 1989, Dybo 2000, Dybo 2011, Yanagisawa 2010, Andersson 2019). According to Dybo's hypothesis, the Proto-Abkhaz-Abaza language had a system of paradigmatic accent with a high (+, D) and low (−, R) tones, which was then reflected in the Abaza and Abkhaz languages. Due to the small amount of information about the Tapanta tonal system, only the stress denoted by acute is reconstructed on the basis of the Abaza and Abkhaz languages.

Abaza (Tapanta) tonal system
Chirikba (1983) in his fieldwork, which has about 100 words, in the Tapanta dialect distinguishes (H) high, (M) mid and (L) low tones. Tones in Tapanta were discovered by Starostin in 1977, unfortunately, Starostin's recording has not been published. Here are some examples below:
 * *la (“dog”) → la (H), definite a-lá (MH), in Dybo's notation la (+), definite a (+) -lá (+).
 * *la (“eye”) → la (M), definite á-la (HM), in Dybo's notation la (−), definite á (+) -la (−).
 * *źʷə (“boiled”) → źə (H), definite a-źə́ (MH), in Dybo's notation źə (+), definite a (+) -źə́ (+).
 * *źʷə (“cow”) → źə (L), definite á-ź (H[L]), in Dybo's notation źə (−), definite á (+) -ź (−).

Valences do not distinguish between the tonal system, but reflect the place of accent. In the first example, the valences suppose a contour of high tones (HH), but in reality it (MH), however, the last and second examples shows that definite article a- has a high (H[L]/M) tone, which is reflected in the dominant valence. So it's more of an internal change. The recessive valence reflects the mid and low tones.

Abkhaz accent system
Abkhaz is characterized by strong dynamic stress, which can fall on any syllable in polysyllabic words. Longer words can have a secondary stress. Less usually, two syllables in a long word can be equally stressed. Stress distinguishes many otherwise homophonic words and wordforms. According to Dybo, this accentual model could be a transformation of an older tonal system. Andersson (2019) demonstrates this as follows:

Descendants
Descendants are listed in alphabetical order. The following is a template that can be copy pasted in new entries: