Alexandria in Susiana or Charax: city at the head of the Persian Gulf.
Alexandria in Susiana was founded in the spring of 324 by the Macedonian conqueror Alexander the Great on an artificial hill between the estuaries of the river Tigris (in the west) and the joint courses of the Eulaeus and Pasitigris (in the east). It was not an entirely new city, because there had been an Achaemenid settlement called Durine on this place. The new settlers were veterans who received a special quarter in the city that was called Pella, after the capital of Macedonia.
The city was soon known as Charax (from Aramaic Karkâ, 'castle') and flourished under the Seleucid Empire, controlling the trade in the Persian Gulf and Indian Ocean. It was also a center for pearl diving.
The new city, however, was destroyed by a river inundation, was refounded by the Seleucid king Antiochus III the Great (222-187) and was briefly called Antiochia. After the Parthian invasion of Mesopotamia in 141, Charax became independent.
According to the Mauritanian king Juba, who wrote several books on ethnography, the satrap who had once served the Seleucid king Antiochus IV Epiphanes, an Iranian named Hyspaosines, became its first king. He is mentioned for the first time in the Astronomical Diaries in 127/126 BCE; the eldest numismatic evidence is from the same period. The port was now called Charax Spasinou, i.e., the Castle of Hyspaosines, and it was the capital of a small state that was known as Characene, Maišan, or Mesene.
The little state kept its independence (perhaps as a vassal of the Parthian Empire) and sometimes joined the Romans in their struggle against the common enemy, the Parthian king. In his Natural history, the Roman author Pliny the Elder praises the port
The embankments extend in length a distance of nearly 4½ kilometers, in breadth a little less. It stood at first at a distance of 1¾ km from the shore, and even had a harbor of its own. But according to Juba, it is 75 kilometer from the sea; and at the present day, the ambassadors from Arabia, and our own merchants who have visited the place, say that it stands at a distance of one 180 kilometers from the sea-shore. Indeed, in no part of the world have alluvial deposits been formed more rapidly by the rivers, and to a greater extent than here; and it is only a matter of surprise that the tides, which run to a considerable distance beyond this city, do not carry them back again.note[Pliny the Elder, Natural History 6.139; tr. John Bostock]
Trade continued to be important and it is probably no coincidence that the most famous Characenian, a man named Isidore, was the author of a treatise on the trade routes in the Parthian Empire, the Mansiones Parthicae. The inhabitants of Palmyra had a permanent trading station in Characene and many inscriptions mention ungoing caravan trade.
Only a couple of Parthian rulers, like Pacorus II (78-105), were able to control Characene directly. Under normal circumstances, it was more or less independent. The twenty-third and last ruler, Abinergaos III, was defeated in 222 by a Persian named Ardašir, who had revolted against his Parthian overlord. His rebellion was successful and he became the first king of the Sasanian Empire. Charax was refounded for a second time when Ardašir settled new people in Charax; in Arabian sources, it is called Karh Maisan.
The city has been identified near the Hayabir hill near Al-Qurna (in Iraq). Surface finds date back to the Sasanian and early Islamic age but excavations have not yet taken place.
Monika Schuol, Die Charakene: Ein mesopotamisches Königreich in hellenistisch-parthischer Zeit (Stuttgart 2000)