Unknown: Al-madd wa-'l-jazr;

(On the cause of the tides) (1192)

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Taken from: A RARE AND UNPUBLISHED MEDIEVAL ISLAMIC MAP by Juan Romero-Girón Deleito, April, 2019

Juan Romero-Giron concludes in his work that the author of this book is unknown. It was written or copied in 1192 in Seville.

In the Royal Library of the Monastery of El Escorial (Spain) there is a manuscript containing a medieval Islamic world map (twelfth century), unpublished and not studied, which presents several peculiar characteristics, and especially, a water inlet on the west coast of Africa that it could be a representation of the Gulf of Guinea, three centuries before its exploration and discovery by the Portuguese.

The manuscript is divided into 30 short chapters, which have a geographical and astronomical content to explain the cause of the tides and the rise of the rivers, with special dedication in chapters 25-29: the rise of the Nile. But chapter 24 has several maps. The chapter is titled: About what is said about the seas that come out of the ocean and what comes from the ebb and flow.

Six are the great outgoing seas of the ocean: three from the eastern region and three from the western one.

- The sea of India (Indian Ocean) leaves the eastern region, in the southern quadrant..... and is the largest of these seas and the richest in straits ...... In it there are all the islands of India and there also flow the Tigris and the Euphrates..... In this sea is the mouth of the Indus, by which the annual flow rises as it rises through the Nile of Egypt.....

- From this Indian Ocean another gulf (Red Sea) passes between the region of Abyssinia and the land of Yemen..... This sea reaches the vicinity of Mecca...... Between this gulf and what unites with the Indian Ocean, which reaches the lowest part of Basra, is the heart of the country of the Arabs.....

- This great sea is opposed in the western region by another sea (Mediterranean Sea) that leaves the ocean in the western part of the country of Sudan, which ends in the vicinity of the Mountains of the Moon and in it are the mouth of the Nile of Egypt, the fertile islands of Sicily and Mallorca and others..... Its length is 6,000 miles and its width is almost 400.

- On the east it is opposed by the sea called Yurian (Caspian Sea) which is said not to join with the ocean......

- The Baltic Sea leaves the western region...... It has many straits and in its lower part there are many islands known as the Islands of the Magi (Name in ancient documents attributed to the Scandinavian countries)......

- Facing the eastern region is the sea of Gog and Magog (Sea of China).....

The geography of the Earth has been drawn by means of two different images, of round and flat shape, so that you can see clearly the way in which the ebb and flow behave and its particularities with respect to the ocean and where ends the monthly flow of these seas, where is the end of that sea and its limits.......