Why couldn't Rome Conquer Arabia?

At the height of its power, the mighty Roman Empire controlled a massive 5 million square kilometers. From Spain to Egypt, the Romans had demolished any armies brave enough to stand in their way. And yet, throughout its rule, there remained a glaring blank space on its map. It was the place that the Romans just couldn't conquer, Arabia. For the Romans, Arabia was the key to an endless supply of lavish riches, silks, and spices, gold and silver. To rule Arabia was to open up trade with the Far East, and from there, who knew, they simply had to have it. Unfortunately, it was never to be. Despite several attempts to invade and secure Arabian lands, the Romans could never quite pull it off. They were prevented by a number of factors, including climate, geography, poor decision making, and a steely Arab resistance. When Augustus became the first Roman emperor in 17 BC, he assumed control of a massive empire. Roman rule spread as far west as Spain, and down into North Africa, including Egypt. Confidence was sky high, and the Romans were hungry for more expansion. Their army was expertly drilled, powerfully armed, and at its peak, had half a million soldiers. The Roman system was simple, expand the empire by simply rampaging over the top of other civilizations, then acquire all wealth from the new territories, and either recruit or enslave the newly conquered populations. This was a largely successful strategy. However, when the Romans turned their attention towards Arabia, they found it to be a desperately difficult region to take control of. The importance of establishing some kind of rule in Arabia was a result of the burgeoning trade with India, and later China. Arabia formed the vital link between Asian civilizations to the east, and the Rome-controlled areas of much of Europe to the west. Rome's upper classes had acquired expensive tastes, and when Augustus became emperor, the demand for exotic spices and silks was very much on the rise. Some of the sought-after spices such as pepper and cinnamon were traded with India, while others such as frankincense and myrrh were only found in Southern Arabia, around today's Yemen. The Arabs, the Sabaeans, transported their spices via an inland trail known as the Incense Route, adjacent to the Red Sea. The Incense Route wound up to northwestern Arabia, near Petra, or modern-day Jordan. The Nabataeans had settled in this region, and they and their Sabaean contacts soon became extremely wealthy on the back of the lucrative trade with Rome. When Rome took control of Egypt in 30 BC, it opened up huge markets for trade between the west and the east. Trade with India and China was now possible via the Red and Arabian Sea Routes, while overland routes from China into Central Asia and then Arabia were also starting to take shape. Although Rome had a small foothold in Arabia, the Romans wanted to set up permanent settlements throughout the region, especially in Southern Arabia, which had ports lined along the Arabian Sea. The Romans saw the Arabian Peninsula as having three regions – Arabian Petra in the north, the vast desert Arabia in the center, and the prosperous and southern Arabia. The Romans called this southern region Arabia Felix, meaning happy or lucky Arabia, because of the region's perceived affluence and economic potential. Augustus wanted to cash in on this part of Arabia and expand Rome's borders. The Romans fancied their chances because it was before the rise of Islam, and Arabia had no central governing body or army. Augustus assumed his vast legions of troops would once again march into a new territory, snap up the spoils, and add another Roman territory to the map. And so, in 26 BC, he ordered one of his Egyptian governors, Gaius Gallus, to head an expedition to Southern Arabia. Augustus' instructions to Gallus were simple – set up client-state relations or take control. Rome had already set up a client-state system with the Navatians in northwestern Arabia in 62 BC. The Roman general Scorus had besieged the Navatian city of Petra, but was fast running out of supplies, and his troops were wilting under the fierce heat. The Navatian king Aretas III struck up a sly deal with the Roman leader. They decided that for an agreed-upon sum, or bribe, the Romans would withdraw and the Navatians would be permitted to continue as an independent client-state of Rome. Aretas paid Scorus a generous amount in gold and silver, which Scorus happily accepted. This allowed the Romans to begin making inroads into Northern Arabia based on the Navatian submission. When Gallus set forth from today's Suez in 25 BC, he had a legionnaire of some 10,000 soldiers, plus another 1,000 Navatians. Supporting the mission were Navatian guides and supply trucks. Gallus had also organized for supply ships to follow him down the Red Sea, so the Roman troops could head to the coast and access supplies as needed. On paper, it looked great. However, right from the outset, the Arabian invasion seemed doomed. The Roman troops crossed the Red Sea from Egypt and disembarked at Loos Qom in northwestern Arabia. Already, scores of men were stricken with stomach viruses, cramps, and fevers that had quickly spread amongst the tightly compressed legions of troops. No sooner had they staggered off the ships and prepared for their southern assault than the Romans were hit by a plague. It was thought to have been caused by a mix of the local waters and plants, and pretty soon, Gallus had to call time and wait until his troops recuperated. Hardly ideal. When the worst of the plague had ended several weeks later, Gallus rallied his troops and outlined the tactics. The plan was to head south to modern-day Yemen and take the city of Marib. The Navatians provided Gallus with a friendly and unassuming guide named Sileus. Despite his charms, Sileus was to play a vital part in the failure of the Gallus-led invasion. Sileus was instructed to lead the Romans along roughly the same path as used by traders on the incense route. Sources at the time, such as Pliny the Elder and Gallus' friend Strabo, had both estimated the trip as needing at least five camel stops, which was a considerable trek. The Romans, largely ignorant of the Arabian geography and brutal desert heat, were about to enter hell itself. Instead of taking Gallus and his men directly to the southern tip, Sileus marched the Romans into the unforgiving desert region of Arabia, where the Roman soldiers soon began to buckle and wilt. The heat was like nothing the Romans had encountered, and before long, hundreds were dead from heat exhaustion and thirst. Not only were Gallus' men deprived of water, but Sileus had taken them away from their coastal supply ships, further exacerbating the situation. Why the deception? The Nabataeans were fiercely proud of their independence, and resented the Roman assumption that they would assist in fighting against other Arabs. Sileus continued southward, always promising that riches were soon to come. Despite the immense hardship, the Romans were able to easily overpower Arab settlements, and the push continued to southern Arabia. Cities such as Medina, Mecca, and Nagrana all fell to the battle-hardened Roman forces, but the desert and lack of food and water were adding up. Gallus was taking serious losses due to the conditions, but Sileus insisted that they push on south. By the time the Romans finally reached the southern Arabian capital of Marib, they were out on their feet. It had taken a staggering six months to march from the northern tip of the peninsula to the south, a journey that was usually only a matter of weeks. Gallus brought his men in and laid out his plans. They were to form a siege of Marib, and eventually take control of what they'd marched so long to attain. However, the Roman troops were exhausted, and many were seriously ill. To make matters worse, the southern Sabian Arabs were well-organized and had the wealth to construct daunting six-meter defensive walls around their capital city. Their soldiers were rested, well-fed, and fresh, ready for a fight. The Romans lasted only six days before Gallus conceded defeat and ordered a humiliating retreat back to Egypt. Not surprisingly, there was no welcoming party for Gallus. Instead, he was relieved of his duties by an enraged Augustus, who started contemplating the next best way to gain a foothold in Arabia. It would be more than a century later, but the Romans tried again to invade Arabia. This time, at least initially, they had some success. In 107 AD, Roman Emperor Trajan had begun a serious assault to the east. He was eyeing the independent Nabataean region of northwestern Arabia. The Romans had previously seized the area under the command of Scarus, but had allowed the Nabataeans to remain independent, on the proviso that they paid for the privilege. When the Nabataean king Rabal died in 106, the Romans moved in. They already had troops stationed in nearby Syria and Egypt, and were easily able to annex the Nabataean kingdom. It became the province of Arabia Petria, and swallowed up portions of modern day Syria, Jordan, and Saudi Arabia. From here, the Romans were able to solidify their position, and for a time, the northwestern chunk of Arabia was under Roman rule. This is what the Romans were after. Partial access to the huge amount of trade passing through northern Arabia and the western empires via the Red Sea. The Romans prospered in the 2nd century, accumulating revenue from traders passing through Arabia Petria, and forming their own trade routes to link up with the east. They formed a handy alliance with the Ghassanid Arabs, who moved up from the south into Syria. The Ghassanids helped the Romans keep their Arab armies at bay, and maintain control of northern Arabia. In the late 2nd century, Emperor Septimus Severus saw firsthand how volatile the region was becoming. He led forces into Syria to put a stop to aggression. This was to be as big as it got, in terms of the Roman presence in Arabia. In the late 3rd century, Emperor Diocletian decided to expand Arabia Petria to include parts of Palestine, and the Arabian region of the empire remained a relatively stable Roman stronghold until the rise of the Arab Muslim Caliphates in the 7th century. So why then didn't the Romans continue their expansion into Arabia? What stopped them from completely conquering the Arab territories? In the end, it was a combination of things. First was the effort and manpower required. Rome simply didn't have the resources. Running an empire is a challenging job, and with its territories stretched as far as Gaul to the west, the thought of further expansion eastwards was probably a bridge too far. Rome had its hands full with the constant repelling of Germanic tribes to the west, and to attempt a full invasion of Arabia would have been too optimistic, to say the least. Added to that were the constant battles fought with Persian armies, who both sought to wrest control of Roman Arabia. Then there were the smaller bands of Arab forces, often fighting amongst each other and resistant to Roman rule. When the Muslim conquest of the Levant kicked off in 634, the Romans were still recuperating from bitter fighting with the Persians. Under the command of the Rashidun Caliphate, Arab Muslims came together to form a formidable alliance that was to ultimately prove too much for the Romans. The Arab armies marched into Roman-occupied Arabia via the Syrian desert, completely taking the Romans by surprise. The Arab Muslims were simply too well-trained and too great in number, and soon took control of what had been Arabia Patria. The Arabs were also used to the desert, the heat, and how to survive in such a trying environment. This was another major deterrent for the Romans. The desert, the heat, and the lack of water. Arabia just wasn't worth the effort.