To reconstruct the process of ethnic changes happened in Georgia at the turn of the millennia, we should track the dynamics of migration of the mountaineers in the Western Georgia.  In the first place we consider Strabo's (64 B.C. - 20 A.D.) information about ethnical situation and location of tribes in the Western Georgia.

Strabo's "Geography" is a source with several strata. Despite this, the author seems to be inclined to write about current situation of that time. According to Strabo to the north-west of Colchis, from Dioskurias (today -Sukhumi), there are settled Akhaioi, east of them Zigi, Heniokhi and Kerketi tribes. First, Strabo writes that after Kerkets' coast there is Akhaioi's coast - 500 stadia long, then Heniokhi coast - 1000 stadia long and coast of great Pitius till Dioskuria - 360 stadia. He took this information from Artemidor (2^nd-1^st cc. B.C.). Then he writes: "narrators of Mithridates' stories, who are more credible, say that at first there are Akhaioi, then Zigi, then Heniokhi, again Kerkets, then Moskhi and Kolkhi" [Strabo, 2, 14, Kaukhchishvili,  1957:120]. In our opinion,  Strabo's conclusion is correct because  this situation is more real in his contemporary times. Despite this, the author mentions Ptheiropags, Svans and other small tribes in the highlands, to the North of above-mentioned tribes [Strabo, 2, 14, Kaukhchishvili, 1957:120]. We see that ethnopolitical changes which took place mostly in the following century (or during the following generation) began. In the 2^nd -1^st cc. B.C. Jiks (Zigs) began inhabiting to the west of Heniokhi. It seems, that Sarmatian tribes appear from 2^nd c. B.C. on the territory of modern Abkhazia  because of the incursion of new waves of  Sarmatian tribes in the 3^rd -2^nd cc. in the North Caucasus and in the South Ukraine. It is notable, that Scythian-Sarmatian type of weapon of the  3^rd-2^nd cc. is discovered in Eshera, near Sokhumi [Inadze, A, 1992:47-48].

Strabo's "small tribes near Caucasus" could be Apsiloi and Abasgi [Letodiani, 1991:6]. It means, that Strabo gives us information about receptio of highlanders coming soon in the times of junior contemporaries of Strabo.

Kolkhi (Colchians) lived from Dioskurias (Sokhumi) till Trapezunt (Trabzon) as mount Trapezunt is mentioned at the border of Tibarania and Kolkhida (Colchis) [Strabo, VII, 4, 3,   12 Kaukhchishvili, 1957:100]. According to Strabo, Kolkheti borders Heniokhi to the north-west, probably the border was at Pitius (Bichvinta) or to the west of it. Kolkheti bordered Caucasus to the north,  the Black Sea to the west and  Trapezunt  to the south-west [S. Janashia, 1988:296].

Strabo mentions Kerkets near Heniokhi and Moskhi. S. Janashia thinks that it can be explained just if we locate them in the northern part of Caucasus [S. Janashia, 1988:302].  Besides this, Strabo mentions Apaits, former Kerkets, at the rocky mountain Skidise, near Sans and lesser Armenia. It seems, they lived on the middle part of the mountains, as Strabo writes that in the very highlands of Skidise lived Heptakomets [Strabo, XII, 3, 18, 12 Kaukhchishvili,  1957:203-204]. In M. Inadze's opinion, the appearance of Circassian population in the Chorokhi river inflow may be explained as migration of one Circassian tribe from north-western coasts of the Black Sea because the soil was barren [Inadze,  B, 1992:162].

The existence of Circassian ethnical substratum in the south regions of Kolkheti seems real if we take into account toponyms connected with Adiygheian world, but we should restrain from making some audacious conclusions, we know that these toponyms are not attested in narrative sources, so we have no opportunity to check chronological frameworks of their origin.

Heptakomets of Strabo are the same of Xenophon's Skvitins. Skvitins - Shkvitins ("škvit" means "seven" in Mengrelian) are Heptakometts of the same inhabitants of seven villages. It seems, this is a union of seven inhabited villages, which ethnically belongs to Mengrelian-Chani tribes. Mosiniki and Bidzers lived near them too.

As to the inhabitance of Moskhi (Meskhi) on the territory of Abkhazia: Moskhi are mentioned in Abkhazia by Helanike of Mitilen (5^th c. B.C.), Palephate of Abidos (4^th c. B.C.) and historians if Mithridatic wars.

The river Parthenios where Palephate mentions Moskhi tribes is Koja-Irmak in Asia Minor. So, he mixes Moskhi tribes which inhabited Abkhazia with the Moskhi which lived in Asia Minor in the 6^th c. B.C. The fact that Moskhi are mentioned to the north-west of  Kerkets means that they lived not in the Abkhazian coast, but in hinterland, in the highlands [Inadze,  B, 1992:162-163].

If we trust this historical tradition, we should locate Moskhis in the upper hinterland of modern Abkhazia in the 6^th-1^st cc. more than in the coastal part, therefore we could explain why Greek authors - Pseudo Skilaks of Kariand (4^th c. B.C.), Artemidorus of Ephesus (3^rd - 2^nd cc B.C.) do not mention Moskhis among tribes, which inhabited from Old Pitius till Tuapse along the coast. Even Strabo does not mention them on the coasts of the Black Sea. Moskhi are attested in the highlands of north Kolkheti by Procopius of Caesarea in the 6^th c. A.D. [Inadze,  B, 1992:163]. 

So, we can assume that perhaps Moskhi tribes inhabited highlands of the northern Colchis. tribes called Moskhi perhaps lived on the territory of Abkhazia, alongside Western-Georgian (Chani-Zani) and Svani population. It means, that the process of Moskhi migration had to begin before antique period (8^th - 7^th cc. ).  During this period Kartvelian tribes - Bidzeri, Katarzai moved from the east to the former center of Kulkha (Kolkha) kingdom and Iganiekhi-Heniokhi ethnical groups moved from Childir lake to eastern coast of the Black Sea [Inadze,  C, 1992:19].  There is a connection between this migration and appearance of toponym "Mtskhetash" in north Colchis (Kolkheti), in Svaneti [Inadze,  B, 1992:164].

It is notable, that the same kind of pottery was discovered in the Sokhumi, in upper Racha and inner Kartli, in Samtavro interment, in the archaeological monuments of 1^st half of 1^st millenium B.C. [Inadze,  C, 1992:20].

Despite this information, N. Lomouri considers that Moskhi tribes never lived on the territory of modern Abkhazia [Lomouri, 1998:25]. In our opinion, even if we ignore the information given by logographers, we can not ignore Strabo's information, because his data are very accurate. We think that Moskhi of Procopius lived not in the north but in the south. In T. Mikeladze's opinion, Meskhi tribes lived in modern Racha and Lechkhumi in the first centuries [Mikeladze,  1974:22].

Ptheirophagi lived in the mountains of Abkhazia, by Strabo. It seems, they settled to the west part, more than Moskhi. It is notable, that Koraxi and Koli are not mentioned in the period of Strabo, earlier they inhabited territory between the river Bzybi and modern Sokhumi, coastal part as well as highlands. Koli must have lived in the lowlands of the Caucasus. We think that Koraxi lived mostly in the north-western part. In M. Inadze's opinion, "small tribes" of Herodotus [Herod. I, 203 Kaukhchishvili,  1975:111],  should be Koli and Koraxi [Inadze,  B, 1992:159]. Perhaps their name is not mentioned because Colchians  name, who lived in the east of Dioskuria by Strabo, covered their names or perhaps they were assimilated by Heniokhi.

In the highlands near Trapezunt and  Farnakia, Tibarani, Khalds and Sani lived by Strabo,which were called Makrons in the earlier periods. It seems, these tribes except Tibarani, lived in mountains to the west of the Apaits, Heptakomets, Mosiniki and Bidzeri.

Historians register fundamental changes on the territory of the Western Georgia after Strabo. From the historians of Mithridates Memnon is the first who mentions Sanigi and Lazi: "successors of Kleokhares seeing this... they sat on the boats and ran to the utmost east regions of Pontus; Sanigi and Lazi lived there"[Memnon, XVII, 54. 7, Kaukhchishvili,  1987:46].

As for Memnon, we do not know the chronology of his life for sure.  Usually he is considered to have lived in 1^st c. B.C. - 1^st c. A.D. but as he mentions Sanigs and Lazi, some historians think that he should be junior contemporary of Strabo. In this case it seems that the very first who mentions Lazi and Sanigi is Pliny the elder.

In our opinion, Memnon describes earlier situation, than Pliny, because Pliny apart from Sanigi and Lazi mentions Apsiloi too. They lived on the small part of the coasts, but if they migrated for that period, they had to be mentioned between Sanigi and Lazi. So Memnon would mention Lazi and Apsiloi or Sanigi and Apsiloi. Besides this, it is possible that Lazi kingdom was perceived as united economical space and Sanigi kingdom as different economical and geographical region.

T. Kaukhchishvili thinks that Lazi of Memnon live near Dioskurias. In our opinion, Lazi influence was spread on Dioskurias, but it does not mean that they were not inhabited in the south of it too. 

Pliny is the first who mentions Apsiloi in the neighborhood of Lazi and Sanigi near the rivers Astelephos (Kodori) and Khrisoroas (Kelasuri). Thus, Apsiloi must have inhabited Kodori (Tsebelda) gorge. Their territory was reached the fortress of Sebastopolis to the north-west and Svani country to the north-east. As for sea coast, Apsiloi should not have held big territory there [Arbolishvili, 2006:21-22]..

In D. Muskhelishvili's opinion toponym which preserved the indication to border of Apsilia and Egrisi  (Lazika) is mount Apshara, which is located on the dividing range  of the upper parts of the rivers Enguri and the Ghalidzga [Muskhelishvili, 1977:118].

Some historians connect Tsebelda pottery of later antiquity with Apsiloi (2^nd-6^th cc.), because this pottery seems to be different from that of Tsebelda of early antiquity [Voronov, 1969:75]. We should note that the elements of Tsebelda culture genetically are in close relation with Colchian-Koban culture, and this indicates that ethno-cultural tradition of Colchian population continues [Todua, 2000:190].

The emergence of alien elements and meanwhile preserving Colchian traditions in  Tsebelda culture is determined by existence of mixed population which consisted of  Lazi and Apsiloi elements.

M. Inadze thinks that Circassian tribes Kerkets that lived in the inflow of Apsaros (Chorokhi) were assimilated with western-Georgian tribes soon but the testament of their Adigheian origin is preserved in the names of the river Apsaros and mythical character Apsirte. Apsiloi who lived in north Colchis, in  Kodori gorge preserved their proper ethnical name much longer, besides, they existed as a separated ethnopolitical unit for centuries [Inadze, A, 1992:53].

We think that on the bases of Apsiloi tribes upper classes were fulfilled and because of this their name was preserved, this region, which was part of Lazika was called after them. This was a denomination of economic and perhaps political importance.

Ethnonym Apsiloi and name of the river Chorokhi "Apsaros, Apsari" in M. Inadze's opinion indicates, that in some regions of Colchis Adyghean ethnical groups existed not later than the 4^th century B.C. Although she mentions that the names with the root "Aps" have Georgian-Zani suffixes (el-il, ar) and this is an indication that Adygheian tribes co-existed with Kartvelian population and during some period were surrounded by Kartvelian ethnical world. Apsiloi tribes were surrounded by Kartvelian tribes earlier than 1^st c. A.D. as their ethnonym - Apsiloi appears in Greco-Roman writing with Georgian suffix [Inadze,  B, 1992:162].

In our opinion, the origination of Apsiloi name with Kartvelian suffix is determined by existence of Mengrelian (perhaps Moskhi) elements in Apsilia. It is notable, that after Strabo ancient authors do not mention Moskhi tribes, they are replaced by Apsiloi as well as other tribes.

Later, the name of Apsiloi was spread on the territory of neighboring Sanigi princedom; at first they occupied its eastern part almost till Anakopia fortress (New Athos). It is attested as a part of Sanigi princedom in the 2^nd c. A.D. and later became the city of Apsiloi [Inadze,  B, 1992:171; Lomouri,  1998:40; Muskhelishvili, 1977:99].

Pliny mentions new tribes - "Sanigi" on the territory of Abkhazia in the 1^st century A.D. For some period tribes with this ethnonym are mentioned as neighbors of Heniokhi, but later at the beginning of the 2^nd c. the union of Heniokhi tribes which consisted of miscellaneous tribes as well as their name disappears in sources. Sanigi princedom replaced Heniokhi princedom. Territory of Sanigi princedom so as Heniokhi princedom included vast territory. Arryan tells, that Sebastopolos (today - Sokhumi) was located on their territory, and they reached even the river Akeunt (today - Shakhe) in the west. [Kaukhchishvili,  1965:159; Inadze,  C, 1992:45].

Memnon mentions just Lazi and Sanigi while narrating about the events concerning Mithridates of Pontus. In M. Inadze's opinion it means, that these ethnical groups were the most important.

To N. Lomouri's mind Sanigi lived from Sokhumi to Gantiadi in the 1^st - 2^nd cc. [Lomouri, 1998:31], but Arryan indicates very clearly that the riv. Akeunt (Shakhe) is a border between Zilki and Sanigi [Fl.Arr. PPE, 18, 11, Kechaghmadze,1961:52].

In 2^nd c. Sanigi held vast coastal territories from Sebastopolis till Akeunt (Shakhe), but in the 5^th century they owned just part of that territory from the river Abaskos (Bzybi, Psou or Mdzimta) till Akeunt (Shakhe), and coastal line from Bzipi till New Athen (Anakopia) was part of the Abasgian political unit [Inadze,  C, 1992:58].

It is notable, that the "Life of Kartli" ("Kartlis Tskhovreba") mentions Sanigi in connection with the events of 12^th century [Life of Kartli , 1959:49]. In our opinion, since 6^th century Sanigi were suppressed by other tribes lived in the highlands. Perhaps they lived in the northern parts of the Caucasus, it would explain the fact they are mentioned together with Kashags (Circassians). In 1^st c. Tacitus (55-56 - after 117 A.D.) mentions Sedokhezi tribe [Tacit. III, 48, Latishev,  1938:315]. Sedokhezi, in our opinion lived at the mouth of the Enguri, as riv. Khobi of  Tacitus is the same riv. Kobos of Arryan, i.e. Enguri. Arryan is the first who mentions Abasgi. "Abasgi are the neighbors of Apsiloi, Resmaga is the king of Abaski, he has received the throne from you too. Sanigi are the neighbors of Abaski, Sebastopolis is on their land" [Fl.Arr. PPE, 11, 11, Kechaghmadze, 1961:43]. The river Abaskos (Psou, Bzybi or Mdzimta) at the influx to the sea,  is on the territory of Sanigi. Perhaps Abasgi still inhabited the highlands and the river was named after the tribe living at the upper reaches.  It seems, Abasgi inhabited the north of the Caucasus till 5^th c. A.D. or perhaps at the upper course of the rivers Psou or Mdzimta, and just after this  period migrated to the Black Sea coast [Gvantseladze,  1993:26-27].

Abasgi hardly reached Sebastopolis in the time of Arryan, but in the 5^th century they lived up to the river Abaskos. Later, in Byzantine period, Abaski lived up to Nikopsia ("Old Lazika" of earlier sources, modern Negopsukho). So, they occupied the whole territory of Sanigi and became neighbors of Jiki. After this just two names remain on the north-east coasts of the Black Sea: Abasgia (Abkhazia) and Jikia (Jiketi) [Melikishvili, 1959:89].

It is difficult to say what kind of coalition was the union of Abasgi and Sanigi. We can not argue what was the language of these mixed tribes - Abasgi and Sanigi. Anyway, in our opinion Sanigi were not replaced totally by Abasgi, we think, that these two tribes, Sanigi from the lowlands and Abasgi from the highlands mixed and the name of Abasgi covered the name of Sanigi, perhaps, because of this very reason Apsilia became the name of neighboring state.

In P.Ingorokvas's opinion, main territory of Abkhazian tribes comprised the highlands of Abkhazia, which included these sectors: 1. middle and upper parts of riv. Bzipi, 2. upper part of riv. Psou, 3. middle and upper part of riv. Mdzimta. In early period, it seems, the center was in Mdzimta ravine and this was called Abaskhi - river of Abkhazians [Ingorokva,  1954:123].

Migration of main ethnical group of Abkhazians from the northern parts of the Caucasus must have happened till the 1^st century A.D. A little later, migration of new waves of Abkhazian-Adigeian tribes strengthened positions of Abaski/Abasgi on this territory[Inadze B, 1992: 171-172].

Apsiloi and Abasgi in 2^nd - 5^th cc. A.D. lived between Sebastopolis and the riv. Abaskos. In 2^nd c. this territory was part of the Sanigi princedom, which stretched from Sebastopolis up to  riv. Akeunt (Shakhe). In later antiquity (not early than 2^nd c.), Lazi tribes of Megrelian-Chani origin took this territory and banished Abkhazians to the north. It is possible, that south-western part of Abkhazian highlands was inhabited by Svani ethnical groups during this period [Anchabadze, 1976:38-40].

At first, N. Lomouri thought that Apsiloi and Abasgi inhabited coasts of the Black Sea from riv. Khobi up to Sebastopolis-Sokhumi and Sanigi lived from Sebastopolis up to riv. Akeunt (Shakhe) [Lomouri, 1968:10]. Part of Apsiloi perhaps lived to the east of the riv. Kodori in 5^th - 6^th cc. in Z. Papaskiri's opinion too [Papaskiri, 2004:27-28]. M. Gunba writes that Apsiloi occupied territory from Dioskurias (Sokhumi) up to the Enguri and their northern boundary was the riv. Gumista or the riv. Kelasur  [Gunba, 1989:140].  Later, N. Lomouri changed his opinion about Abkhazian population in the region of Gali and in the left coast of the riv. Enguri: Apsiloi and Abasgi of Arryan are ancestors of modern Abkhazians but most distant south boundary of their inhabitance never reached the riv. Ghalidzga [Lomouri,  1996:79].  Abkhazian tribes never inhabited the territory of modern Gali region, even at the earliest stages of their history. Gali was always politically and ethnically part of Lazika (Egrisi). At the beginning of 5^th c. as a result of gradual political strengthening of Lazika Kingdom, the boundary between Lazi and Apsiloi changed and was moved to the riv. Kodori, Lazi forced out Apsiloi and Apsiloi removed Abasgi [Lomouri, 1998:34, 40].

Perhaps the influence of Lazi (Egri) tribes grew on the north-west coast of riv. Rioni as Argveti was controlled by Kartli. This would hinder settlement of Abasgi between Apsiloi and Sanigi [Letodiani, 1991:9].

In our opinion, no ethnical movement took place, in this case, one political unit covered the name of another one, and population was mixed - Megrelian-Abkhazian, ethnically as well as linguistically since 1^st - 2^nd cc.

So, uniting of Abasgi with the west Georgian tribes Sanigi on the coasts of the Black Sea began not in the 5^th - 7^th centuries but in early period, although it is notable that part of Abasgi, especially who lived in mountains preserved their ethnicity and the fact that Procopius mentions Sanigi, not Zelki (Jiki) as western neighbors of Abasgi, indicates that the name of Abasgi covered the names of other tribes of Georgian ethnicity (Sanigi - i.e. Heniokhi of earlier period, Koraxi, Koli).

The boundary between Apsiloi and Abasgi became Trakea, which in historians' opinion was  Anakopia (modern Akhali Atoni) on the riv. Gumista, or Gagra. Abasgi moved to the north before 5^th c. They occupied territory between the rivers Gumista and Psou. Sanigi controlled just little coastal territory between Psou and Shakhe, across Shakhe lived Jiki [Lomouri, 1998:40; Muskhelishvili,  1977:99].

Later sources (Hippolytus of Rome, Eusebius of Caesarea, Procopius of Caesarea, Justinian, Agathias Scholasticus) do not know anything about Abasgi living on the coasts between Apsiloi and Sanigi up to Sebastopolis-Tskhum. Besides, there is no any source, which would indicate that Apsiloi and Abasgi totally replaced Sanigi. Sani-Sanigi did not move out from their place of inhabitance. In the 3^rd - 4^th centuries they still lived on the territory where Pliny and Ariane located them. The anonymous writer of the 5^th century does not know any other ethnos from Sebastopolis up to Pitius except Sanigi and they were part of the Kolkheti (Lazika) Kingdom in the 5^th century. Besides this, in D. Letodiani's opinion, if Apsiloi and Abasgi were neighbors on the coasts, then it would be natural that Byzantine forces would come (?) either on the territory of Apsiloi or Abasgi, not between them. They came on the territory of Sanigi. Procopius is the first who mentions Abasgi on the coasts of the sea, and locates them near Trakea (modern Gagra or Akhali Atoni). Hence, Abasgi migrated from the north Caucasus to the coasts of the Black Sea not early than the 5^th century and from this period they inhabited the territory just in the region of modern Gagra or Akhali Atoni (Anakopia). Kartvelian tribes lived not only up to Shakhe, which bordered Sanigi and Jiki, but to the north-west of it [Letodiani, 1991:22-34]. Although, it is notable that toponym "Old Lazika" of Arryan indicates that, once, before Arryan's times, this whole territory up to Nikopsia (Negopsukho) was part of Lazi economic space.