Dating world maps
Ptolemy discussed and favored this revised figure of Posidonius over Eratosthenes in his Geographia, and during the Middle Ages scholars divided into two camps regarding the circumference of the Earth, one side identifying with Eratosthenes' calculation and the other with Posidonius' 180,000 stadion measure.
He measured the Earth's circumference by reference to the position of the star Canopus.
One on Europe, is essentially a periplus of the Mediterranean, describing each region in turn, reaching as far north as Scythia.
The other book, on Asia, is arranged similarly to the Periplus of the Erythraean Sea of which a version of the 1st century CE survives.
Within the books of Geographica is a map of Europe.
Whole world maps according to Strabo are reconstructions from his written text.
Eratosthenes (276–194 BCE) drew an improved world map, incorporating information from the campaigns of Alexander the Great and his successors.