Commercial roads made civilizations meet and influence each other.
The most important road was the “Silk Road”, which extended for approximately 8000 km. It was constituted by land, sea and river courses which hgranted commerce between the Chinese Empire ant the Western civilization. Caravan roads crossed central Asia and Middle East, and they connected Chang’an (the actual Xi'an), in China, to Minor Asia and the Mediterranean Sea. The name of the road was used for the first time in 1877 by the German geographer Ferdinand von Richthofen (1833-1905) in his work Tagebucher aus China. Von Richthofen referred to the Seidenstraße, the «Silk Road», in the introduction.
The final destionation of silk (and of other precious goods) was Rome; other equally precious goods were travelling it the opposite direction. The fundamental concepts of Maths, Geometry and Astronomy were travelling with the goods, and Religions were doing the same: Manichaesim and Nestorianism were going eastbound, while Buddhism was moving form India to Central Asia, China and Tibet, trying to find a way to avoid the Himalaya mountains. These commercial and cultural exchanges determined the development of ancient civilizations as in Egypt, China, India and Rome, but they were also important for the birth of the modern world.
Some sources assert that Caesar brought some enemy flags form Anatolia: the unknown tissue of those flags was silk. The only known thing about that tissue at that time was that it came from some undefined land of Seres. Plinius thought it was woven from a very thin wire, which was made from the hair of unknown leaves, that he called the forest wool. The Roman Senate tried to forbid the use of silk, which was considered a decadent and immoral tissue. The real reason of this prohibition was probably the big amount of gold that was leaving Rome to buy this tissue.
Constantinople had a privileged geographic position: at the times of Justinian, it controlled all the commercial traffic in the Mediterranean area. Byzantines were not interested in commerce with European countries, which were poor due to the Barbaric invasions; they preferred contacts with Extreme Eastern countries, such as China, were silk was made. Chinese people imported Byzantine crockery and Syrian tissues and exported silk.
Persia was a great hindrance for the commerce with Extreme East. It was an enemy territory for the Empire, though it was necessary to cross it to reach China. This meant that during the wars with the Sassanian Persians, commerce with China and India was not possible. Giustiniano looked for a passage to China through Crimea, and this brought the Byzantines to develop diplomatic relations with the Turks, who were also fighting with the Sassanians. Justinian also tried to reach China crossing the Red Sea and the Indian Ocean. This brought to commercial relations with the Ethiopians in the Reign of Aksum. Anyway, both the alternative ways were inconvenient: the Indian Ocean was controlled by the Sassanians, and the Asiatic way was very risky.
The problem was solved by two monks from China, or from some near region, who reached Constantinople in 552: they told the Emperor the secret of silk production. The Emperor entrusted them to provide some eggs of silkworms, and to bring them in Constantinople, to allow the Byzantines to produce silk. Many years passed before the self produced silk was enough to satisfy the internal demand, so the Byzantines kept importing silk from China through Persia for a long period. After, the production of silk was one of the most important sectors for Byzantine Industry.
In the Commune Age, Italian merchants were controlling commerce by use of their codes: spices were a very important part of traffics. Spice sellers inherited precise professional rules from monks. They had their organizations that selected species from the East and established both the norms for quality and prices. Those norms were collected in the first known pharmacopoeia, the Ricettario Fiorentino by the Medical Council of Florence in 1496. Every spice seller was obliged to prepare herb medicines following the prescriptions: heavy sanctions were adopted against violators of norms. The Ricettario indicated the quality of spices for medicines, and this influenced the commerce. Spices reached Florence through the docks of Pisa and Livorno, and they were commercialized all over Italy. Venice also had a primary political role due to the control of routes for Asian goods in the Aegean Sea.
The “Tin Road” is more ancient and mysterious. The Cassiterides were the mythical islands of tin, (cassiteros = tin); many classical authors localized them outside the Pillars of Hercules, in the Atlantic Ocean. Other authors referred to Britain, others to different islands on the Tin Route from Britain. So the existence of these Islands is uncertain.
Comemrcial routes through the Sahara Desert were the only roads between Mediterranean countries and Western Africa from the 8th to the end of the 16th century. Commerce was carried out by camel caravans: those animals were fed for months in Maghreb or Sahel, and then they were used to form a caravan. Ibn Battuta was a Maroquine traveler who lived with the Tuaregs and followed a caravan. Caravans could be formed from 1000 to 12000 camels. There were contacts between populations on the opposite sides of the desert also during Prehistory. Commercial routes along the Nile connected Lower Egypt to Nubia, and they were run 3000 years before Christ, that is at the beginning of civilization, while the journey across the desert was impossible until the domestication of camel. Mediterranean economies needed gold to forge coins, but they could give salt, while Western African countries had a lot of gold and they needed salt. This commerce helped the spreading of Islamic culture. The Portuguese reached the western coast of Africa, and they started new commercial routes between Europe and western Africa. Within the first half of the 16th century, sea commerce became very important for western African countries. North Africa suffered a political and economical decline, while the routes across the Sahara desert were long and risky, so they were progressively abandoned.