The Seven Zones

The ancient philosophers divided the cultivated part of the earth in the north into 7 zones by means of imaginary lines running from west to east. They maintain that these zones have different latitudinal extensions.

Zone 1 runs along the equator, north of it.

South of it, there is only the civilization to which reference was made by Ptolemy. Beyond that are waste regions and sandy deserts, up to the circle of water which is called the Surrounding Sea.

To the north, Zone 1 is followed successively by Zone 2 through Zone 7.

Zone 7 constitutes the northern limit of civilization. Beyond it are only empty and waste regions, down to the Surrounding Sea as (in the south).

However, the empty regions in the south are much larger than those in the north.*

As to latitudes and length of days in the various zones, the 2 poles of the firmament are on the horizon at the equator in the west and the east.

The sun there is at the zenith. As we follow the cultivated part of the earth farther and farther north, the north pole ascends slightly, and the south pole descends correspondingly, (at the horizon).

Furthermore, the sun moves a corresponding distance from (its zenith at) the equinoctial line. These 3 distances are equal to each other. Each of them is called geographical latitude. This is well known to the scholars who determine the prayer times.

People hold different opinions as to:

• the latitudinal extension of the cultivated part of the earth and
• the latitudinal extension (width) of the various zones.

Ptolemy thinks that the latitudinal extension of the entire cultivated part of the earth is 771/ 2 .

The latitudinal extension of the cultivated part beyond the equator to the south is 11°.

Thus, the latitudinal extension of the zones in the north is 66 1.

According to him:

• Zone 1 extends to 16°
• Zone 2 extends to 20°
• Zone 3 extends to 27°
• Zone 4 extends to 33°
• Zone 5 extends to 38°
• Zone 6 extends to 43°
• Zone 7 extends to 48°

He then determined the degree on the firmament as having a length of 662/ miles, were it measured on the surface of the earth.

• Zone 1 from south to north is 1,067 miles wide
• Zone 2 is 2,333 miles
• Zone 3 is 2,790 miles
• Zone 4 is 2,185 miles
• Zone 5 is 2,520 miles
• Zone 6 is 2,840 miles
• Zone 7 is 3,150 miles

The length of night and day differs in the various zones because of:

• the declination of the sun from the equinoctial line
• the elevation of the north pole above the horizon.

This causes a difference in the arcs of day and night.

At the boundary of the first zone, the longest night-which occurs when the sun enters Capricorn-and the longest day which occurs when the sun enters Cancer-reach a maximum of 13 hours. The same is the case at the boundary of Zone 2 in the north.

The length of day there reaches its maximum of 13.5 hours when the sun enters Cancer, the summer tropic.

The longest night -when the sun enters Capricorn, the winter tropic is as long. For the shortest day and night, there thus remains the difference between 13.5 and 24, which is the combined number of hours of day and night, or one complete revolution of the firmament.

The same is the case also at the boundary of:

• Zone 3 in the north, where night and day reach a maximum length of 14 hours;
• Zone 4, where they reach a maximum length of 14.5 hours
• Zone 5, where they reach a maximum length of 15 hours
• Zone 6, where they reach a maximum length of 15.5 hours
• Zone 7, where they reach a maximum length of 16 hours.

There, civilization ends.

The difference in the maximum length of night and day in the various zones, consequently, is an evenly distributed, gradual increase of half an hour in each, all the way from the first zone in the south to the last zone in the north.

In connection with these zones, “geographical latitude” refers to the distance between the sun at its zenith in a given place and the equinoctial line where it is at thezenith on the equator.

It likewise corresponds to the depression of the south pole below the horizon in that particular place, as well as to the elevation of the north pole.

These 3 distances are equal to each other. They are called “geographical latitude.”

According to Ptolemy, the longest night which occurs when the sun enters Capricorn - and the longest day-which occurs when the sun enters Cancer-reach

• a maximum of 12.5 hours at the boundary of Zone 1
• a maximum of 13 hours at the boundary of Zone 2
• a maximum of 13.5 hours at the boundary of Zone 3
• a maximum of 14 hours at the boundary of Zone 4
• a maximum of 14.5 hours at the boundary of Zone 5
• a maximum of 15 hours at the boundary of Zone 6
• a maximum of 15.5 hours at the boundary of Zone 7

For the shortest day and night, there thus remains the difference between the last figure and 24, which is the combined number of hours of day and night, or one complete revolution of the firmament.

The difference in the maximum length of night and day in the various zones, consequently, is an evenly distributed, gradual increase of half an hour in each, all the way from the first zone in the south to the last zone in the north.*

Ishaq b. al-Hasan al-Khazini thinks that the latitudinal extension of civilization beyond the equator (to the south) is 16 ° 25’, and the longest night and day there, 13 hours.

The latitudinal extension of Zone 1 and the length of day and night there are the same as beyond the equator (to the south).

Zone 2 extends to 24°, and the length of its (longest) day and night at its farthest point is 13.5 hours.

For Zone 3, it is 30° and 14 hours.

For Zone 4, it is 36° and 14.5 hours.

For Zone 5, it is 41° and 15 hours.

For Zone 6, it is 45° and 15.5 hours.

For Zone 7, it is 48.5° and 16 hours.

The latitudinal extension of civilization beyond Zone 7 to the north reaches from the boundary of Zone 7 to latitude 63 ° , and the length of the (longest) day and night to twenty hours.

Other leading scholars in the discipline, apart from Ishaq al-Khazini, maintain that the latitudinal extension of the cultivated area beyond the equator (to the south) is 16 ° 27'.

The first zone extends to 20 ° 15’; the second to 27 ° 13’; the third to 33 ° 20’; the fourth to 38 1 / 2 ° ; 52 the fifth to 43 ° ; the sixth to 47 ° 53’; or, according to another opinion, to 46 ° 50';

The seventh to 51 ° 53’. Civilization beyond the seventh zone extends to 77 ° .

Abu Jafar al-Khazini is one of the leading scholars in the discipline. He also finds that the latitudinal extension of the first zone is from 1 ° to 20 ° 13’; of the second, to 27 ° 13’; of the third, to 33° 39’; of the fourth, to 38° 23’; of the fifth, to 42 ° 58’; of the sixth, to 47 ° 2’; and of the seventh, to 60°45'.

The geographers have subdivided each of the 7 zones lengthwise from west to east in ten equal sections.

They mention the countries, cities, mountains, and rivers of each section, and the traveling distances between them. We shall now briefly summarize the best-known countries, rivers, and seas of each section.

Our model will be the data set forth in the Nuzhat al-mushtaq which al-‘Alawi al-Idrisi al-Hammudi composed for the Christian king of Sicily, Roger, the son of Roger.

Al-Idrisi’s family had given up its rule of Malaga. He had settled at (Roger’s) court in Sicily.

He wrote the book in the mid-12th century.

He utilized many books by authors such as al-Mas’udi, Ibn Khurradadhbih, al-Hawgali, al-‘Udhri, Ishaq al-Munajjim, 57 Ptolemy and others.