The outpost was 600 miles from the nearest Roman port, Berenice on the Egyptian side of the Red Sea, 1,200 miles south of Alexandria, 3,000 miles from the city of Rome, and more than 4,000 miles from Hadrian's Wall on the northern borders of the empire.
To understand why there was a Roman presence deep in the Red Sea we need to discuss Rome's eastern expansion and the critical economic role played by its trade with southern Arabia, India and, to a lesser extent, Ethiopia and Somalia. It was during the 1st century BC that Rome first came into extensive direct contact with these areas. Pompey the Great's campaigns during the 60s resulted in Syria and Judea becoming provinces and client kingdoms of Rome. Caesar's victory in the civil war with Antony and Cleopatra led to Egypt becoming a Roman province in 30 and Nabataea, with its famous capital of Petra, situated east of the Sinai and south of Judea, submitting as a client kingdom.
The civil war settlement created opportunities and problems. At the end of the war there were sixty Roman legions still in the field, perhaps more than 500,000 soldiers including auxiliaries. Augustus needed to disband some of these units but also find a way to field a large enough army to protect the expanded borders of the empire. His solution was to create a professional, paid army of 28 legions (nearly 300,000 including auxiliaries). Soldiers would serve for 20 years and upon retirement be granted a pension.
Where would the funds come to support the army? Estimates are that perhaps 70% of the Empire's annual spending was needed to pay for the army. Rome had relatively light taxes on its provinces and many of the newly acquired border lands did not provide enough revenue to support the legions stationed there. The light taxation was part of the deal which kept newly conquered lands quiescent and willing to assimilate into Roman ways.
Part of the solution was Egypt, an astonishingly wealthy land by classical standards, with a flourishing agricultural sector and trading connections to the East. Egypt alone may have contributed 1/3 of the revenue of the Roman Empire and in the immediate wake of Augustus' annexation increased Rome's revenue by more than 50%. Egypt was so important that Augustus, and his successors, retained it under their direct rule. Roman senators were not allowed to visit Egypt except if permitted by the emperor and its governor was always appointed from the lower equestrian class.
By that time, Egypt had already opened up direct trade with India from the Red Sea ports of Myos Hormos and Bernice. In 118 BC, a Ptolemaic ship had rescued an Indian sailor blown off course in the Indian Ocean. From him, they learned the secrets of the monsoon winds and how to use them to sail in the late summer for India and return in late winter. At the time of the Roman conquest perhaps a couple of dozen ships were sailing each year from Egypt to India or to points in between where Indian traders would meet them.
But with Rome's increased wealth and the exposure of its upper classes to the exotic goods of Arabia Felix (modern Yemen and Oman) and India, trade exploded. By the first century AD over 100 ships a year were sailing directly from Egypt to India with countless others visiting points between in Africa and Arabia. To accomplish this, the two ports were improved and Rome established and protected a road network from the town of Coptos on the Nile to the ports. Travelers were required to have government issued permits in order to travel from Coptos to the ports.
It was a twelve day sail down the Nile from Alexandria to Coptos and seven to twelve days further to the ports. The army established watering stations and garrisons to protect caravans from raiders. Along the trail extensive commercial operations could be found - granite and porphyry quarries along with emerald and gold mines. Along with trade goods the road network also allowed for support of the working populations in the ports (it's been estimated that 500 camel loads a month were required to support Berenice). This required a substantial investment in infrastructure and commitment of sizable military forces. It was paid for by a 25% tax on all imports (this contrasts with a 2.5% tax on goods traveling between Roman provinces, a tax from which Italy was exempt). The revenue from the tax became a substantial contributor to the budget of the empire and aided in maintaining the legions.
What was it that attracted the Romans? The best description of this trade can be found in The Roman Empire and the Indian Ocean: The Ancient World Economy and the Kingdoms of Africa, Arabia and India (2014) by Raoul McLaughlin (some of the conclusions the author draws regarding the relative economic value of the trade and its economic contribution to the Roman state are made on very sketchy and extrapolated data and should be used with caution, but his overall picture of the trade is enlightening).
"Eastern goods transformed Roman culture by offering new food flavorings, perfumes, medical remedies, jewellery styles and clothing fashions. As Piny the Elder observed, 'people used to gather their ingredients from home and there was no demand for Indian pepper and these other luxuries that we now import from overseas'."Another concise description of trade can be found in the New Testament: Revelations 18:23 (early Christians referred to Rome as Babylon). I've boldfaced those items obtained from the eastern trade:
"The town houses and country villas of wealthy Romans were stocked with fashionable ornamental furniture made from ebony and other exotic woods, embellished with bright turtle shells veneers and ivory inlays. These materials were used to make dining couches, centrepiece tables and more private furniture, including beds."
"your businessmen are the most powerful in the entire earth and with your bewitchments you have deceived all the nations of the world . . .. merchandise of gold, silver, jewels, pearls and fine linen, purple, silk and scarlet, all kinds of scented wood, ivory, articles of costly wood, bronze, iron and marble, cinnamon, spice, incense, myrrh and frankincense".The last three on the list were primarily supplied by Arabia Felix, which obtained the Latin designation of Felix because of what was viewed as its favorable climate, its protected geography (to the north lay the desert and to all other sides the ocean), and the wealth generated by its products (which also included gold and gems). Some of the incense crops could also be found in Somalia, while pearls came from both the Red Sea and India. India was the source of spices, of which the most important was pepper, along with gemstones which McLaughlin describes as "a stunning range of gems with a bewildering variety of colours and attractive properties."
There were also other exotic imports from the area such as wild animals from Ethiopia and Somalia and tortoise shells. More mundane items also show up. Rome's monumental structures required enormous amounts of cut marble and it was discovered that the best cutting sands to aid in the process came from Ethiopia prompting it to become a major import.
Roman ships also sailed down the east coast of Africa as far as Zanzibar to trade. They routinely visited the Tamil kingdoms of south India, where Roman artisans and ex-soldiers were recruited to serve as carpenters and mercenaries for the royal families. The chief port of the area had a permanent Roman presence, including Jews and early Christians, that grew into the thousands in the late fall when the ships arrived with the monsoon.
In 52 AD direct communication was opened between Rome and Taprobane (Sri Lanka) when a freedman of the Alexandria trader Publius Annius Plocamus was caught in gale, swept out to sea. The freedman obtained an audience with the king, who was impressed enough to send an embassy to Emperor Claudius. Claudius gave a gift of red coral, a material highly valued in India and Taprobane, to the embassy which was donated by the king to a Buddhist temple which remained celebrated as a treasure from "Romanukha" in local literature a thousand years later. Direct sailing from Egypt to Taprobane commenced and soon Roman ships began exploring up east coast of India. By the early second century Ptolemy listed sixty cities and ports on the east coast all the way to the Ganges Delta in Bengal and Bangladesh. The most venturesome of Roman captains made it as far as Tamala on the northwest edge of the Malay peninsula.
The demand during for goods during the first and second centuries AD caused the trade to grow and it generated huge profits for businessmen (one pound of incense cost the equivalent of 50 days of wages for a skilled labourer) and substantial tax revenues for the empire. The demand was so high that the second century orator Aristides proclaimed:
"there is clothing from Babylon and ornaments from the barbarian world beyond . . . there are so many cargoes from India and Arabia Felix that you might imagine that their trees have now been left bare . . ."There was always a delicate economic calculation in determining whether it was more valuable to the empire to annex new territories or whether it was more profitable to maintain trade arrangements from which more substantial tax revenues could be derived.
In the time of Augustus (at least until the disaster in the Teutoberg forest of Germania in 9 AD) the balance weighed in favor of expansion. After the acquisition of Egypt and Nabataea becoming a client kingdom Rome became fully aware of the wealth of Arabia Felix. The Nabataeans in particular maintained a lucrative land and sea trade, serving as middlemen for the incense trade. Augustus decided to conquer Arabia Felix and specifically the kingdom of Sabea in the mountains of northern Yemen, which lies approximately across the waterway from the Farasan Islands.
To accomplish this task the Roman governor of Egypt, Aelius Gallus, led an expedition in 25 BC. A fleet was built to support the effort and two legions marched overland from Nabataea. A march of 80 days brought them several hundred miles south nearing the Sabean capital. But severe disease (possibly scurvy) struck Gallus' force and he ordered a retreat. Upon his return Gallus advised Augustus that Arabia Felix could not be conquered by soldiers from the Mediterranean, putting an end to Roman expansion into Arabia. However, one beneficiary byproduct to Rome was that its campaign destabilized the Sabean regime which was overthrown. The new rulers of the Saba-Himyarite Kingdom were friendly to Rome, opening their ports to direct trade.
Over the next century, relations between the Saba-Himyarites, Nabataeans, and Romans remained cordial. The Nabataeans patrolled the Red Sea coast protecting their ships from pirates and trade prospered.
In 106 AD the situation changed. With the death of the Nabataean king, Emperor Trajan decided to annex his lands and make it the Roman province of Arabia. Rome took over direct management of the trade routes. Soon thereafter we have the first inscription documenting the Roman garrison on the Farasans. Whether the Romans took over a pre-existing Nabataean fort, were invited by the Saba-Himyarites, or just decided on their own to occupy the islands is unknown. The troops were a detachment from Legio VI Ferrata, whose home base was in Nabataea.
The specific purpose of the Roman garrison can only be speculated upon. The islands were only 60 miles from the main Saba port of Muza and 120 miles from the important Ethiopian port of Adulis on the western shore of the Red Sea. It was also not too far from the rich pearl fisheries in the Strait of Bab-el-Mandeb at the southern entrance of the Red Sea. The garrison, along with elements of the Roman fleet, could have helped suppress pirates and protect the nearby ports, pearl fisheries, and Nabataean trading settlements in Somalia, as well as serving as a customs outpost.
Trajan may have had a longer term plan in mind as well. In 115 Trajan invaded Parthia, captured its capital and reached the Persian Gulf. If he had succeeded in maintaining that conquest, it's possible that reviving Roman plans to occupy Arabia Felix may have been next and the Farasan garrison might have been an advance force.
However, with Trajan's withdrawal from Parthia any such plans were cancelled though the Farasan garrison remained in place. What did change is how it was garrisoned. The second inscription recently discovered dates to 143-44 and is by garrison commander Castricius Aprinus, described as Prefect of the Port of Farasan and of the Sea of Hercules (Bab-el-Mandeb). The title indicates the formality of Roman occupation and its wide ranging scope. Aprinus is also from the Roman legion stationed in Egypt. The change is a likely indicator of the relative decline in the importance of Nabataean trade and the growing significance in Egypt's connections with the East.
We have no evidence on when the Farasan garrison was withdrawn. Perhaps, now that the two inscriptions have been discovered additional archaeological work may help answer that question.
There is one last intriguing aspect of Rome's connection with the East. In 166, the chronicles of China's Han Dynasty record a Roman delegation from Marcus Aurelius having an audience with the Han Emperor. There are two schools of historical thought about this "delegation". One that it was merely a group of Roman merchants who branded themselves as a formal embassy to obtain access to the emperor, the second that Marcus Aurelius really did send an embassy on a merchant ship possibly to seek Chinese support in his planned expedition against Parthia. There was to be no followup from Rome.
A couple of years before the Roman delegation reached China, the Han army on its northwest frontier suffered an epidemic outbreak of disease. Up to a third of China's soldiers may have died. The epidemic moved west along trade routes, reaching Parthia and then infecting the Roman armies in the East who has they returned carried the disease into Rome's European territories. What became known as the Antonine Pandemic killed untold millions in the Roman Empire, weakening its armies and economy. At the same time, the invasions of Germanic tribes across the Danube began, even penetrating into Italy at one point. Countering this threat was to preoccupy Aurelius until the end of his reign in 180 (events portrayed in a fanciful, and very entertaining, way in the movie Gladiator). Though Aurelius ultimately triumphed, Rome's treasury was exhausted.
Trade and eastern connections were further damaged by the events of the third century. Rome went through a chaotic period from 235 to 284 with civil war and almost fifty emperors and pretenders. The Parthians were overthrown by the Sassanians who posed a greater threat to Rome. The most powerful of the Indian kingdoms Rome had traded with also broke up during this century leading to more unsettled conditions, and the Han dynasty collapsed in 220 leading to a long period of instability in China.
Behind all this was a long term economic conundrum that Rome could not solve. Rome's appetite for eastern luxury goods was insatiable. But while there were certain goods desired in Arabia and India in exchange (wine, red coral, furniture, tableware, art) it was not enough to pay for Roman imports. The difference had to be made up by gold and silver bullion (often in the form of coins). By later in the second century Rome's primary sources for both, much of which were located in Spain, were in decline, leading to both devaluation of currency and difficulty in financing imports. At the same time, as trade declined Rome's tax revenue from imports also declined impacting its ability to support the army.