The term ‘portolan chart’ first occurs in Italy in the thirteenth century, not long after this aid to navigation came into general use on board ship. The Italian word portolano, however, can best be translated as ‘pilot book’ or ‘sailing directions’, a different aid to navigation of which one example survives from the fourth century b.c., and pilot books are indeed still published in modern form by all seafaring nations. References by Herodotus in the History make it probable that such documents already existed in his time, and under the name of periplus they continued up to the sixth century a.d.; after which they do not appear again until the golden age of navigation in Italy and Catalonia in the late Middle Ages, apart from some much simpler early medieval types. The portolano or periplus is a description of ports, with information required by the navigator concerning anchorages, dangers threatening landfall and the winds and weather over wider areas. Commercial information was sometimes included, obviously also a matter of interest to the mariner who could read, though it may be doubted if many of them then could.

Italian portolan charts exist from almost the same period as the portolani, both of them denoted by the same word compasso, but while the pilot books have their modern successors the charts were only produced up to the beginning of the seventeenth century and are not really the forerunners of the modern sea chart.