The prevailing view is that the Portuguese made the famous nautical chart. But that is very unlikely, according to a Dutch researcher.

The story of the Cantino planisphere reads like an exciting boys’ book. At the behest of Portuguese explorers – who had dared to descend further and further along the African west coast and then discovered that you could circumnavigate the continent – ​​cartographers at the end of the fifteenth century are said to have produced an extremely up-to-date and beautiful map on which the African coastlines are depicted with remarkable accuracy. A showpiece that eventually ends up in the hands of Italian spy Alberto Cantino, who smuggles the map back to his homeland, where it can be found – much to the chagrin of the Portuguese – to this day.

Not Portuguese

It’s a beautiful story. But is it also true? Did the Portuguese really make the map? A new study is calling into question that established opinion in the history of cartography. in the sheet Terra Incognita researcher Roel Nicolai states that it is very unlikely that the oldest surviving nautical chart of Africa was drawn up on the instructions of Portuguese explorers. Who actually made the map is an intriguing mystery.

The Cantino planisphere (planisphere means world map) is 2.20 by 1.05 meters in size and made up of six sheets of parchment glued together. The map is hand drawn and shows Africa very prominently in particular. But the adjacent Mediterranean Sea and Europe above are also accurately depicted. In addition, the map also shows Southeast Asia, a part of Greenland, Newfoundland and a newly discovered part of South America.

“The established opinion is that the Portuguese made the map,” confirms Nicolai, who is a geodetic engineer (map maker). “After 1434 – stimulated by the Portuguese Prince Henry the Navigator – Portuguese explorers continued to descend a little further along the African coast, hoping to find a sea route from Africa to India and thus gain access to the spice trade, which was very lucrative. ” At the end of the fifteenth century it becomes clear that it is indeed possible to sail around Africa and in 1497 the famous explorer Vasco da Gama manages to sail – via the Cape of Good Hope – to India. Based on history – the many voyages, first along the west and later also along the east coast of Africa – the Portuguese would have been the best people to come up with the first accurate nautical chart of Africa. But Nicolai thus undermines that assumption. “I won’t be that popular in Portugal right now,” he jokes. But as a mapmaker, he’s pretty confident: the ancient Portuguese didn’t have the knowledge and methods needed to map Africa as accurately as they did on the Cantino planisphere.


Nicolai bases his conclusion on a mathematical analysis of the nautical chart. This shows, among other things, that African coastlines along the Atlantic and Indian Ocean on the Cantino planisphere are made up of seven or eight sub-maps, all of which have the same projection. It indicates that they are all based on an unknown source map with that same projection. “The so-called true-to-life cylinder projection.” It means that whoever made these sub-maps – or the source map they are based on – incorporated the spherical shape of the Earth into them. It is a strong indication that the Portuguese had nothing to do with it. Because even though they were aware of the fact that the Earth was round, they didn’t incorporate that knowledge into their maps. “We know how the Portuguese navigated and made maps – they have documented that extensively – and that’s not where that projection should come from.” In addition, the Cantino planisphere lacks the deformations associated with those Portuguese navigation methods and cartography.

Forgotten or misunderstood civilization?

It naturally raises the question of who made the sub-maps – or the source maps unknown to us on which they are based. The mapmaker is not aware of any medieval cartographic tradition capable of producing such maps. “Such a civilization must have had considerable capabilities to do this,” Nicolai said. “One must have known how big the Earth is, understood projections and had great mathematical knowledge. And if we look back in time, there is not a single culture – known to us – that had those qualities in that period.” And so the intriguing possibility arises that the share maps – or the source map they are based on – are the work of a civilization that we don’t (yet) know. Another – also intriguing possibility – is that they are the work of a civilization that we are familiar with, but which we – perhaps without being aware of – misunderstand and thus underestimate.

postage cards

Incidentally, it is not the first time that Nicolai thinks he has glimpsed such a forgotten or misunderstood civilization. Years ago, he already looked into eight medieval portolan maps. Dating from the 13th to 15th centuries, the maps show the Mediterranean (remarkably, the mysterious cartographer who crafted the Cantino planisphere seems to have used these portolan maps as source maps for his depiction of the Mediterranean). “What my research showed was that those portolan maps were far too accurate for that time,” Nicolai says. “As far as we know, at that time people didn’t have the navigational instruments and the knowledge to make such maps. In addition, the portolan cards also have a map projection. And map projections were still unknown in the Middle Ages.” And thus these maps also hint at a mysterious cartographic tradition.


Years ago, Nicolai cautiously suggested for the portolan maps that we might have to look for this tradition in the corners of the ancient Greeks and Romans, but that hypothesis does not seem an option for the Cantino planisphere. “The portolan maps have appeared in the coastal regions near Genoa, and I suspect that the Genoese – who traded much with the Byzantines – bought them in Constantinople and made numerous copies of them. Since the Byzantines hardly made any maps – they saw Constantinople as the center of the world and felt that traders should come to them instead of the other way around – the portolan maps in this scenario would not have been made by the Byzantines. Instead, they might have been part of the rich Greco-Roman heritage that the Byzantines fell into the lap of.” That possibility had to be kept open for the mysterious portolan maps, but the enigmatic Cantino planisphere with the whole of Africa on it shows that the source maps cannot be from Greco-Roman times. “For the Greeks and Romans were not so southward.”

And so it remains guesswork. It is unclear whether we can ever determine with certainty who measured and mapped Africa so accurately before the Cantino planisphere. “There is nothing else to discover on the maps. So new evidence would have to come from archeology after all,” thinks Nicolai. He then thinks, for example, of finds that fit poorly into our image of history and can therefore hint at an unknown civilization or force us to reconsider our view of an existing civilization. “I think that’s the most important implication of my research,” says Nicolai. “That our picture of history is still incomplete.”