In addition to the mansiones, some taverns offered accommodation as well as food and drink; one recorded tab for a stay showed charges for wine, bread, mule feed, and the services of a prostitute. Trade and commodities Roman provinces traded among themselves, but trade extended outside the frontiers to regions as far away as China and India. The main commodity was grain. Chinese trade was mostly conducted overland through middle men along the Silk Road; Indian trade, however, also occurred by sea from Egyptian ports on the Red Sea. Along these trade paths, the horse, upon which Roman expansion and commerce depended, was one of the main channels through which disease spread. Also in transit for trade were olive oil, various foodstuffs, garum (fish sauce), slaves, ore and manufactured metal objects, fibres and textiles, timber, pottery, glassware, marble, papyrus, spices and materia medica, ivory, pearls, and gemstones. Though most provinces were capable of producing wine, regional varietals were desirable and wine was a central item of trade. Shortages of vin ordinaire were rare. The major suppliers for the city of Rome were the west coast of Italy, southern Gaul, the Tarraconensis region of Hispania, and Crete. Alexandria, the second-largest city, imported wine from Laodicea in Syria and the Aegean. At the retail level, taverns or specialty wine shops (vinaria) sold wine by the jug for carryout and by the drink on premises, with price ranges reflecting quality. Labour and occupations Inscriptions record 268 different occupations in the city of Rome, and 85 in Pompeii. Professional associations or trade guilds (collegia) are attested for a wide range of occupations, including fishermen (piscatores), salt merchants (salinatores), olive oil dealers (olivarii), entertainers (scaenici), cattle dealers (pecuarii), goldsmiths (aurifices), teamsters (asinarii or muliones), and stonecutters (lapidarii). These are sometimes quite specialized: one collegium at Rome was strictly limited to craftsmen who worked in ivory and citrus wood. Work performed by slaves falls into five general categories: domestic, with epitaphs recording at least 55 different household jobs; imperial or public service; urban crafts and services; agriculture; and mining. Convicts provided much of the labour in the mines or quarries, where conditions were notoriously brutal. In practice, there was little division of labour between slave and free, and most workers were illiterate and without special skills. The greatest number of common labourers were employed in agriculture: in the Italian system of industrial farming (latifundia), these may