An Edible History of Humanity by Tom Standage Page A

example by the references in Roman
     sources to cloves, which grew only in the Molucca Islands on the other side of the globe. Spices brought a flavor of southeast
     Asia to Roman tables and the scent of Arabia to Chinese temples. And as spices were traded around the world, they carried
     other things along with them.

    Old World trade networks of the first century a.d. linked the Mediterranean in the west with China and the spice islands in
     the east.
    FREIGHTED WITH MEANING
    Goods are not the only things that flow along trade routes. New inventions, languages, artistic styles, social customs, and
     religious beliefs, as well as physical goods, are also carried around the world by traders. So it was that knowledge of wine
     and wine-making traveled from the Near East to China in the first century A.D.; and knowledge of noodles traveled back in
     the other direction. Other ideas soon followed, including paper, the magnetic compass, and gunpowder. Arabic numerals actually
     originated in India, but they were transmitted to Europe by Arab traders, which explains their name. Hellenistic influences
     are clearly visible in the art and architecture of the Kushan culture of northern India; Venetian buildings were decorated
     with Arab flourishes. But in two fields in particular—geography and religion—the interplay between trade and the transmission
     of knowledge was mutually reinforcing.
    One of the things that makes spices seem so exotic is their association with mysterious, far-off lands. For early geographers
     in the ancient world, attempting to put together the first maps and descriptions of the world, spices often marked the boundaries
     of their knowledge. Strabo, for example, referred to “the Indian cinnamon-producing country” which lay “on the edge of the
     habitable world,” beyond which the earth was, he said, too hot to allow humans to live. Even the more worldly author of the
     Periplus had little idea what happened east of the mouth of the Ganges: there was a large island, “the last place of the habitable
     world” (possibly Sumatra), after which “the sea comes to an end somewhere.” To the north was the mysterious land of “Thina”
     (China), the source of silk and malabathrum (cinnamon) leaves.
    Traders and geographers depended on each other: Traders needed maps, and mapmakers needed information. Traders would visit
     geographers before setting out, and might then share information on their return. Knowing how many days it took to travel
     from one point to another, or typical itineraries of particular routes, made estimates of distance possible, and hence the
     construction of maps. In this way geographers learned about the layout of the world as an indirect result of the trade in
     spices and other goods. This is also why so much information about spices comes from the early geographers. Neither they nor
     the traders wanted to reveal all their secrets, but some give and take made sense for both parties. Merchants worked hand
     in hand with mapmakers, culminating in the map compiled in the second century A.D. by Ptolemy, a Roman mathematician, astronomer,
     and geographer. It was surprisingly accurate by modern standards and formed the basis of Western geography for more than a
     thousand years.
    The interdependence between geography and trade was pointed out by Ptolemy himself, who noted that it was only due to commerce
     that the location of the Stone Tower, a key trading post on the Silk Road to China, was known. He was well aware that the
     Earth was spherical, something that had been demonstrated by Greek philosophers hundreds of years earlier, and he agonized
     about how best to represent it on a flat surface. But Ptolemy’s estimate of the circumference of the Earth was wrong. Although
     Eratosthenes, a Greek mathematician, had calculated the circumference of the Earth four hundred years earlier and arrived
     at almost exactly the right answer, Ptolemy’s figure was one-sixth