Thanks to an article in History Today I have discovered the Stanford University Orbis map which allows you to plan a journey round the Roman Empire circa 200 AD, make choices about which mode of transport you want to use, whether you prefer travelling by road or sea, and specify what load you are carrying. It even tells you how much it will cost! It’s a kind of Man in Trireme 61.
It enabled me to check the journey times and methods used by Posidonius in my novel. Even though he was travelling 300 years earlier, I judge the Orbis map is still probably still valid for the sea and land journeys within the Empire and a rough guide for Posidonius’s journey through unconquered Gaul.
John Freeman in his book on Posidonius: The Philosopher and the Druids charts an odyssey for Posidonius, in which he sails from Rhodes to Cadiz, then sets sail for Marseilles, but gets blown off course along the North African coast, ending up in Rome. From there he travels to Marseilles by land. This route has the virtue of accounting for all of the places we know he visited including his sighting of monkeys in an island off Africa, which we know was on the way from Cadiz to Italy.
By making Posidonius take the land route from Rome to Marseilles, Freeman can fit in his journey to Liguria en route. However, it is difficult to see why Posidonius would have chosen to go by land when it was quicker, and cheaper, by sea. We know that he did, at some point in his life, visit Liguria, but it could have been later, around the time he was Rhodes’ ambassador to Rome. In Liguria his host was a man from Massilia. Couldn’t that have been a friendship formed on his earlier journey?