Strabo

Geography, 11.3.1

Furthermore, the greater part of Iberia is so well built up in respect to cities and farmsteads that their roofs are tiled, and their houses as well as their marketplaces and other public buildings are constructed with architectural skill.
Parts of the country are surrounded by the Caucasian Mountains; for branches of these mountains, as I said before, project towards the south; they are fruitful, comprise the whole of Iberia, and border on both Armenia and Colchis. In the middle is a plain intersected by rivers, the largest being the Cyrus. This river has its beginning in Armenia, flows immediately into the plain above-mentioned, receives both the Aragus, which flows from the Caucasus, and other streams, and empties through a narrow valley into Albania; and between the valley and Armenia it flows in great volume through plains that have exceedingly good pasture, receives still more rivers, among which are the Alazonius, Sandobanes, Rhoetaces, and Chanes, all navigable, and empties into the Caspian Sea. It was formerly called Corus.

Now the plain of the Iberians is inhabited by people who are rather inclined to farming and to peace, and they dress after both the Armenian and the Median fashion; but the major, or warlike, portion occupy the mountainous territory, living like the Scythians and the Sarmatians, of whom they are both neighbors and kinsmen; however, they engage also in farming. And they assemble many tens of thousands, both from their own people and from the Scythians and Sarmatians, whenever anything alarming occurs.

There are four passes leading into their country; one through Sarapana, a Colchian stronghold, and through the narrow defiles there. Through these defiles the Phasis, which has been made passable by one hundred and twenty bridges because of the windings of its course, flows down into Colchis with rough and violent stream, the region being cut into ravines by many torrents at the time of the heavy rains. The Phasis rises in the mountains that lie above it, where it is supplied by many springs; and in the plains it receives still other rivers, among which are the Glaucus and the Hippus. Thus filled and having by now become navigable, it issues forth into the Pontus; and it has on its banks a city bearing the same name; and near it is a lake. Such, then, is the pass that leads from Colchis into Iberia, being shut in by rocks, by strongholds, and by rivers that run through ravines.

From the country of the nomads on the north there is a difficult ascent into Iberia requiring three days' travel; and after this ascent comes a narrow valley on the Aragus River, with a single file road requiring a four days' journey. The end of the road is guarded by a fortress which is hard to capture. The pass leading from Albania into Iberia is at first hewn through rock, and then leads through a marsh formed by the River Alazonius, which falls from the Caucasus. The passes from Armenia into Iberia are the defiles on the Cyrus and those on the Aragus. For, before the two rivers meet, they have on their banks fortified cities that are situated upon rocks, these being about sixteen stadia distant from each other--I mean Harmozice on the Cyrus and Seusamora on the other river. These passes were used first by Pompey when he set out from the country of the Armenians, and afterwards by Canidius.

There are also four castes among the inhabitants of Iberia. One, and the first of all, is that from which they appoint their kings, the appointee being both the nearest of kin to his predecessor and the eldest, whereas the second in line administers justice and commands the army. The second caste is that of the priests, who among other things attend to all matters of controversy with the neighboring peoples. The third is that of the soldiers and the farmers. And the fourth is that of the common people, who are slaves of the king and perform all the services that pertain to human livelihood. Their possessions are held in common by them according to families, although the eldest is ruler and steward of each estate. Such are the Iberians and their country.