In the past thirty years there has been a massive increase in the number of known wrecks in the Mediterranean, many of which have been excavated. The evidence is, however, difficult to interpret. It is clear that one of the largest staples of trade was grain. However, when a grain ship is wrecked the grain disperses, the ship reaches the bottom empty and is broken up by currents. Not a single wreck of a grain ship has yet been found. A ship carrying amphorae or marble, on the other hand, sinks with its cargo to the bottom and the hull is often protected by their weight and so remains in place to be rediscovered. The number of known wrecks begins to go into decline in the second century ad although those carrying marble reach a new peak, understandably in view of the great building programmes of the cities. So one might say that trade, other than in marble, was in decline but there is also evidence that amphorae were being replaced by wooden barrels which would, of course, disintegrate fairly soon after a wreck leaving the ship itself exposed to the elements. So a decline in the number of wrecks found is not necessarily an indication of failing trade.
After 150 Bc the size of ships grew steadily and during the republic there are already ships as large as 450-500 tonnes. The Albenga shipwreck of 100 to 90 BC, for instance, was of this size. It was carrying wine from Italy to southern Gaul and had some 10,000 amphorae on board, no less than some 260,000 litres of wine. As the Gauls were known to pay well for their wines this represented an enormous investment, all in this case lost on the seabed. Between 100 Bc and ad 200 there is good evidence for larger ships carrying amphorae and marble of between 300 and 500 tonnes. Grain ships must have been even larger. They had excellent harbour facilities in Alexandria and Carthage and at Portus, the harbour constructed by Claudius and Trajan close to Ostia. Some estimates suggest that the grain ships could have reached 1,000 to 1,300 tonnes. There is a literary reference to a ship of 1,200 tonnes, the Isis, by the second-century ad writer Lucian. These figures remain speculative until actual examples are found.
Amphorae were the ubiquitous storage jar, carrying wine, oil, fish products, even nuts and preserved fruits. There is good evidence that they carried vast quantities of wine to Gaul in the republican period. In the first and second centuries ad, there was a substantial increase in amphorae carrying salted fish and garum, a spicy fish sauce. The extent of the trade can be gauged from the spread of salting factories. The salting pans were placed where the migrations of fish allowed for enormous catches, far greater than would be needed for local consumption. Between ad 50 and ad 200 there was a steady flow of fish products from factories in southern Spain and north Africa. A new processing area began in Brittany in the second half of the first century ad with a surge in production after ad 150 when the second largest known factory in the Roman world at Polmarc’h became active. Inscriptions suggest that the established entrepreneurs had moved up from the factories in the Mediterranean. It was uncommon, however, for a ship to carry a single staple. So the wreck known as Port Vendres II, dated to the 40s ad, is of a ship making its way along the coast from Spain towards Gaul, aiming either to offload its cargo on the Rhone or at an Italian port. It appears to have had the goods of eleven distinct merchants. The amphorae contained wine and olive oil and fish sauce, with smaller decorative items such as glass, fine pottery, and metalware, tin, copper, and lead.
As only a tiny section of the population had the spare capital to buy such items, the market for these smaller luxury items was, inevitably, small as a proportion of the whole, though some commodities such as silverware were popular among a wider clientele. Stamped amphorae suggest a discriminating market for the better-quality goods from elite areas of production, claret-type wine from southern Italy (marked with the name of the estate and the vintage), the heady white Falerian wine that was a favourite of Horace and Catullus, Spanish fish sauce, and oil from Baetica (in the province of Further Spain). The important cloth industry had its own specialist centres, Sicily and Malta, for the most luxurious cloths. In his Natural History, Pliny talks of the best flax coming from eastern Spain with two centres in Italy running it a close second.
Of course, trade was not confined to the Mediterranean. Ivory came in from eastern Africa (via Nubia), incense and myrrh from Arabia, amber from the Baltic coast. Routes spread far towards the east, including into India. Roman coins there, discovered in increasing numbers in the nineteenth century, were first treated as no more than curiosities but there are now enough to show that imported silver coins peaked in the reigns of Augustus and Tiberius (and were often recycled with new markings to use as local coinage). The coins, gold, wine, and olive oil made up the Roman exports. Arikamedu, near modern Pondicherry, was a well-placed port, situated on the coast but with access by water inland, and so developed into an entrepot for the trade. Excavations have uncovered warehouses, amphorae, and first-century Arretine ware. Perfumes, spices, primarily pepper and cardamon, ivory, gemstones, and textiles from as far east as China were brought back across the Arabian Sea and then channelled through Alexandria. The only documented case of a ship returning from India, from the mid-second century, records a value of goods equivalent to 23,000 tonnes of wheat, so there were rich pickings to be had for the owners as well as the numerous artisans who reworked the materials when they arrived in Egypt. Many goods went on to Rome where they were stored in vast warehouses, the horrea, on the banks of the Tiber. Rome was certainly a bustling commercial city. Pliny the Elder lists nine different types of writing paper, twelve kinds of plums, and twenty-seven varieties of linen on sale there and it is assumed that vanished commodities of the fallen Babylon set out in chapter 8 of the Book of Revelation are inspired by those luxuries available in Rome. (See further Claire Holleran, Shopping in Ancient Rome, Oxford, 2012.)
In the first century ad many commodities could command an empire-wide market but the trend was for local production to rival these foreign imports and this may be one reason for an apparent decline in Mediterranean trade in the second century ad. The origin of Samian ware was Arezzo in central Italy where the clay was especially fine and from where the pottery was exported. New centres of production then appeared in Gaul, first at Lugdunum and later southern Gaul. An analysis of amphorae found in shipwrecks show that Spanish and Gallic Samian ware became more important during the first century ad. The kilns at La Graufesenque in south-west France could fire 30,000 high-quality pots in a single firing and the products were sold throughout western Europe and across to the coast of north Africa. Standards were high as can be seen from the pits full of rejected ‘seconds. From this period on it is only occasionally that a local industry achieves a market extending beyond its neighbouring provinces. One example is the astonishing success of African pottery after the second century Bc. It is found penetrating the eastern Mediterranean and even the Black Sea. Gallic cloth and clothing became the fashion in Italy in the third century.
The rise of provincial craftsmanship meant that many raw materials would now be processed at their destination. The copper, tin, and lead of the Port Vendres shipwreck would have been worked up in Gaul or Italy. The area around Capua in Campania was particularly known for its work in copper and silver. The imperial mint at Lyon was using lead and silver from Spain. Lead from Britain has been found in the coins of Augustus, Tiberius, and Nero. Marble was cut in rough shapes, and these became standardized with time so that one could order column shafts and capitals, even sarcophagi with garlands and swags outlined on the sides, direct from the quarry. Surfaces were left rough because any finer work might have been damaged in transport. Some unfinished temples, Didyma in Asia Minor, for instance, have wall surfaces that were never smoothed. A standardized statue form, nude or clothed in a toga, would be left unfinished so that the local recipients could add in the head of the man to be honoured. Altogether the patterns of production were becoming more complex.