from
https://bigthink.com/strange-maps/al-idrisi-map/

Best to go to the citation to view the artwork.

(One, IMHO, key part, what they knew ---
"the cartographer knew full well the world was round, and in fact in the
introduction calculated its circumference as 22,900 miles (37,000 km),
within 10% of the actual length (24,901 miles; 40,075 km)." )

The medieval mapmaker remembered for the wrong map
The history of cartography might have been very different if the Latin
version of Muhammad al-Idrisi's atlas had survived instead of the Arabic
one.
A painting of a man with a turban and a map.
Arab cartographer Muhammad al-Idrisi and the map that he is most
associated with, even though his own atlas doesn’t mention it. (Credit:
DeAgostini / Getty Images, left; Fine Art Images / Heritage Images /
Getty Images, right)
KEY TAKEAWAYS
In the 12th century, a Muslim nobleman named Muhammad al-Idrisi combined
Greek, Arab, and Viking geographic knowledge. In so doing, he created
one of the most detailed and precise world maps of the Middle Ages. Yet
the work he is remembered for is a miniature version of his massive map,
doing him an injustice.

Frank Jacobs
Copy a link to the article entitled
http://The%20medieval%20mapmaker%20remembered%20for%20the%20wrong%20map

If you know one thing about 12th-century Arab cartographer Muhammad
al-Idrisi, it is that he is the author of this wonky world map, which is
often included in modern atlases as a prime example of medieval
mapmaking skills.

That invites comparisons that do him no favors. Among the hyper-precise
maps in today’s atlases, al-Idrisi’s looks like a child’s drawing. His
Europe is sketchy, his Asia amorphous, and his Africa manages to be both
partial and oversized. Plus, the map is a planisphere — the projection
of a sphere onto a flat (and typically circular) plane — which creates
the mistaken impression that al-Idrisi was a flat-Earther of the
Discworld variety.

A map of the world with a boat on it.
Arab maps were oriented toward the south, so this version of the
al-Idrisi map, though more recognizable, is the wrong way up. (Credit:
Universal History Archive / Getty Images)
And that’s not all that’s wrong with this map. For starters, you’re
seeing it upside-down. As did most Arab maps of that time, this one has
south at the top. This was to help recent converts to Islam, most of
whom lived north of Arabia, orient themselves toward Mecca. Moreover,
this map is not by al-Idrisi himself. It’s a vignette that only shows up
in some of the copied manuscripts and isn’t mentioned in the original
text of the atlas. That text describes al-Idrisi’s own maps, which are
much bigger and vastly more detailed.

A poor summary of a massive talent
So, this little map is a poor summary of a massive talent. Al-Idrisi’s
main achievement, a huge atlas known as the Book of Roger, would remain
authoritative for hundreds of years. His concept of the upper reaches of
the Nile was basically confirmed by 19th-century European explorers. And
the man’s biography is as exceptional as his work. Born in 1100 AD in
the North African port city of Ceuta, al-Idrisi was the scion of a noble
family that descended from Imam Ali, the Prophet Muhammad’s cousin, and
thus had a claim to the caliphate. His ancestors had ruled Malaga, in
Muslim Spain.

Al-Idrisi studied in Cordoba and traveled widely as a young man,
visiting Asia Minor, Hungary, the French Atlantic coast, and even as far
north as York, England. In 1138, Roger II, the Norman king of Sicily,
invited al-Idrisi to his court at Palermo, possibly to explore whether
he could install the Muslim nobleman as a puppet ruler in the bits of
North Africa under his dominion, or in Spain, which he hoped to conquer.

An open book with a map of the sea.
Map of the Indian Ocean, from al-Idrisi’s Book of Roger. No monsters,
but still rather imprecise. (Credit: Public domain)
As it turns out, al-Idrisi was more valuable as a scholar. Roger engaged
him to produce a new and accurate map of the world. This proved to be a
huge undertaking and would take 15 years to complete.

With help from the king, the cartographer interviewed ship’s crews and
other seasoned travelers, but retained only those stories on which all
were in agreement, leaving out the more improbable reports. So, there
are no sciapods (a mythical tribe of one-legged people) or other
imaginary monsters on al-Idrisi’s map.

When in doubt, send a scout
Al-Idrisi also consulted older geographic compendia, notably Ptolemy’s
Geography, as well as Islamic works. And if all that still left things
in doubt, he could always ask the king to send out scouts to check or
complement the available information.

The job was finished in 1154. Al-Idrisi had created a world map engraved
on a 300-pound, 6.5-foot (2-m) wide silver disk. He also ranslated the
information on that planisphere onto rectangular maps, each of which was
exhaustively annotated. That atlas is known in Arabic as Nuzhat
al-mushtāq fi’khtirāq āl-āfāq (translated variously as “The book of
pleasant journeys into faraway lands,” or “The excursion of the one who
yearns to penetrate the horizons”), and in Latin commonly as the Tabula
Rogeriana (“Book of Roger”).

Uniquely, it brought together the geographic insights of Greeks, Arabs,
and Vikings, three well-traveled civilizations, producing a world map
more wide-ranging and, thanks to al-Idrisi’s rigorous methodology, more
accurate than any that had gone before.

A map of the world with a yellow background.
AI-Idrisi’s world map, reconstituted from the 70 maps in the Book of
Roger. It is much more detailed than the planisphere, although the
latter is much more famous. Note that this map, with north at the top,
is upside-down, as can be seen from the Roman numerals at the bottom.
The correct version is oriented toward the south. (Credit: Fine Art
Images / Heritage Images / Getty Images)
One of the more intriguing mentions in the Book of Roger is of
Irlandah-al-Kabirah (“Great Ireland”), one day’s sailing from Iceland.
Considering the Viking input he had, this is quite probably a reference
to Greenland.

Al-Idrisi’s atlas consisted of 70 sectional maps covering the entire
known world, ten for each of the Earth’s seven climatic zones (a concept
borrowed from Ptolemy). Accompanying each map was a description of that
area’s terrain, culture, politics, and economy — descriptions that
became more succinct the further away the maps were from Sicily.

When compiled together, those 70 maps make up a huge and detailed map of
the known world of more than 9 feet (2.7 m) long. This is al-Idrisi’s
greatest achievement. The circular world map was only added to later
editions of the atlas, and it exists in several versions. The one shown
here (and used most often) is from the so-called Istanbul Manuscript, a
copy of the Book of Roger made in 1469 by Ali ibn Hasan al-Ajami.

Within 10% of the actual circumference
Despite the standard rendition of al-Idrisi’s worldview as a flat disk,
the cartographer knew full well the world was round, and in fact in the
introduction calculated its circumference as 22,900 miles (37,000 km),
within 10% of the actual length (24,901 miles; 40,075 km).

Roger II was able to enjoy the fruits of al-Idrisi’s work for only a
short while. He died within weeks of its completion. The original Latin
version of the atlas (and the silver disk) were destroyed in 1160 in the
chaos of a coup against William the Wicked, Roger’s unpopular son and
successor. Al-Idrisi fled to North Africa with the version in Arabic,
ensuring that the Book of Roger would remain influential in the Islamic
world, by showing the benefits of a scientific approach to mapmaking,
based on observation and precision.

A map of the world in yellow and blue.
The world map as al-Idrisi intended it, with south on top. (Credit: Fine
Art Images / Heritage Images / Getty Images)
Just one example of al-Idrisi’s influence: As one of the first Arab
cartographers to mention the Silla dynasty in Korea, he helped fix that
kingdom in the imagination of generations of Arab traders as an
alluringly rich and exotic destination for trade.

Al-Idrisi’s impact on European mapmaking, on the other hand, was very
limited. Had the original Latin version of the Book of Roger survived,
Europe’s history of mapmaking and exploration might have turned out
differently. The first new translation of the atlas into Latin, by the
Maronite scholar Gabriel Sionita and known as the Geographia Nubiensis,
was published in Paris as late as 1619. Only in the 19th century, with
the rise of academic Oriental studies, did Europeans come to realize
that al-Idrisi had produced one of the most detailed and precise world
maps of the Middle Ages.

Only ten copies in existence
There are only ten manuscript copies of the Book of Roger in existence,
of which only five have the complete text. Eight have maps, and six do
not have the circular map mentioned in the text itself. The Istanbul
Manuscript is the most complete, having all 70 maps.

A statue of a man holding up a piece of paper.
Al-Idrisi’s statue in Ceuta, showing his map to the world — the proper
version this time, rectangular and “upside-down.” (Credit: Vardulia, CC
BY-SA 3.0)
Al-Idrisi was also called al-Sharif, or “the high-born,” yet despite his
noble lineage never wielded power, political or spiritual. His other
honorific, “father of geography,” is a shared prize at best. The people
of Ceuta know their native son deserves better and should be remembered
for more than that simplified planisphere.