The Sasanian west comprised the regions largely inhabited by an Aramaic-speaking population but including both settled and nomadic Arabs. It was organized into four provinces, whose patter was followed in the Nestorian hyparchies formalized in 410: Meshan (Maisan); Asuristan (Beth Armaye); Garmid ud Nodarashiragan (Beth Garmai, Hedhayyabh); Arbayistan (Beth 'Arbaye).
Meshan combined the Parthian vassal kingdoms of Mesene and Characene; it reached north along the Shatt al-'Arab and then the lower Tigris to Madhar, possibly somewhat beyond. Its key urban centers were the three ports on the upper estuary, which eclipsed the more ancient delta port of Teredon. Farthest north lay the Alexandrian foundation eventually called Spasinou Charax (Karkha dhe Maisan). It has recently been identified with the site at Jabal Khayabir, along the ancient bed of the Karkha toward its former confluence with the Shatt. Here, loosely under Parthian authority, converged caracans from Susa, Gerrha, and especially Seleucia or its emporium, Vologesias. Twelve miles downstream lay Perat dhe Maisan. Both these cities wer refouned by Ardashir I (*Starabad-Ardashir and *Vahman-Ardashir respectively), were bishoprics, and may have contained Sasanian mints. Below Perat, the city of Apologos (Ubulla) was an official emporium in the first century A.D. Its importance in the Gulf trade continued. The emperors Honorius and Theodosius designated it in 408/409 as the Gulf's center for transactions in the silk business; the Nestorian metropolitan was residing there in 424-35, rather than in Perat.
The Semitic inhabitants of this region are divided by Strabo into "Chaldeans" (Aramaic speakers) and Mesenian Arabs (xvi.i.8). The raiding, nomadic Arabs to the west must have added to the population, and the Nabataean and Palmyrene merchants as well. Not only Iranians settled there under the Sasanians, but some of the transported Zutt. The latter were more numerous toward the swamps of Asuristan; they included the sabaj- if not Indians, possibly Malays taken captive in Hind or recruited there as sailors. The idol of Zun seen by the invading Arabs at Ubulla may have belonged to a colony of deportees or of merchants from the Indian frontier. The province was notably fertile, the best one for barley, according to Strabo. Sesame oil was produced, and dates in abundance. The 19th century estimate of 2,150,000 date palms between Basra and Muhammara and beyond it may well be less than the number in the Sasanian period. Already Strabo knew of a "Persian song" extolling the many uses of the date palm; the Middle Persian Drakht i asurig is perhaps only one version. Many of the dried dates imported into the Roman emprie may well have been grown in Meshan.
From its days as the Seleucid "eparchy of the Red Sea" (Polybius v.46.7), Meshan played a vital role in the sea trade along the Gulf and on to India. But neither the Seleucids nor the Parthians achieved Alexander's ambition of unifying the coast (Strabo xvi.1.9-11). Perhaps the Arabian port of Gerrha was as much a partner of Charax and Apologos as a rival. Some Mesenians lived there; they could have been active in importing from Arabia Felix and Africa aromatics, ivory, and such curiosities as the ostriches presented by a Parthian embassy to the Chinese in AD 101. A more serious rival may have been Ommana. If that city lay on the north shor of the Gulf, possibly in the Hurmuz straits, it would have diverted trade to the kingdom of Persis; goods would then have been carried overland to Seleucia. Ommana received cargoes of Arabian aromatics and of ebony, teak, and sandal from the Indian port of Barygasa (Broach). Other merchandise could have reached Ommana or Meshan from Barbaricum, the major port on the Indus.
Roman rivaly in the sea trade with India became increasingly serious after the monssons became utilized for direct sailing to Barygaza, Muziris (Cranganore), and down the Malabar coast; Arab intermediaries were no longer necessary. By the end of the 1st Century AD, some Roman ships were reaching the Ganges and the Golden Chersonesus of Malaya. It is hardly surprising that a Roman "embassy" had reached China from India by 166. Its exports, such as amber, coral, copper, tin, glass, and woolen fabrics, were already reaching Oc-eo, the entrepot of the Fu-man kingdom on the Mekong. Of the goods which remained in India, some moved north to the Kushan kingdom, perhaps accompanied by a considerable amount of specie. The Kushans, in return, directed a share of the Chinese and central Asian land trade to Indian ports. The range of goods exported to Roman Egypt and to Meshan (where a few Kushan coins have been found) emerges from the Periplus and the 3rd Century Alexandrian tarrif-list. "Indian drugs, spices" are the most numerous items, including pepper, ginger, cinnamon and cassia, aloes, galbanum, assafoetida, malabathrum and spikenard. Precious and semi-precius stones, pearls, ivory, and tortoise-shell formed another major category. Fabrics included silks, cottons, and muslins; silk thread was also shipped and perhaps another type of thread named "Indian hair". "Indian steel", "Indian lions and lionesses" are also mentioned. Fur pelts were brought from Transoxiana and Central Asia. It is perhaps these "Seric skins" and "Tokhar martens" which the tariff list terms "babylonian furs, Parthian furs".
Sasanian control of the trade route through Tukharistan was complemented by hegemony in the Gulf and as far as the Indus. The south shore of the Persian Gulf, from Bahrain at least as far as Cape Macae at the straits, was formed into the province of Mazon. While 'Uman was important enough to be organized as a diocese, the majority of Iranian and Mesenian residents apparently concentrated around Bahrain. Ardashir, in order to secure the region, founded the city of Paniyat-Ardashir on the coast, in the district of Qatif. The city functioned as a bishopric by 576; two others were on the islands of Tarut and Muharraq. The seats of government, however, was Gerrha (Hajar); in late Sasanian times it had a community of Jews as well as of Zoroastrians and Nestorians. The Sasanians thus controlled the beds of pearls so highly esteemed in Sanskrit lapidaries. Other likely exports to India (and to Oc-eo) are the products noted by Hsuan-Tsiang: carpets, finished silk and woolen fabrics, garments of felt and skin.
Roman trade with India continued in the Sasanian period. Thus the "scholasticus of Thebes" journeyed to Malabar not long before 350; and an Indian embassy reached Julian in 362 (Ammianus Marcellinus xxii.7.10). For the 6th century, Cosmas Indicopleustes depicts the rivalry of Axumite and Byzantine merchants with the Persians on the west coast ("India Interior"); and it was through India that monks reached Central Asia and smuggled back silkworm eggs (Procopius, Wars viii.17.1-8). But at that time it was the Iranians who dominated the Indian ports, and the Christians there were under the church hyparchy of Fars. The continuing involvement of Iran with India is indicated by the exchange of embassies between Khusrau II and the king of the Deccan.

-The Cambridge History of Iran, vol. 3(2): The Seleucid, Parthian, and Sasanian Periods, ed. Ehsan Yarshater (NY: Cambridge UP, 1983), 754-757.