Population Crises and Population Cycles

The ‘dry belt’ of North Africa and Western Asia extends from Morocco to the centre of the Asian continent. It was called the dry belt by W.M.S. Russell in 1967, because throughout its extent rainfall is irregular and often scanty. There are large areas, notably in flood plains, where the soil can be enormously fertile, and support a very dense population, provided it is suitably irrigated and drained. But these settled enclaves are everywhere bordered by seasonal grasslands merging into totally arid desert. Instead of a homogeneous land-mass with grasslands on its northern border, as in China, the belt is a mosaic of juxtaposed areas of settlement and more or less nomadic herding peoples. Hence it was only once, and briefly, politically unified, by the Arabs in the early eighth century AD. But ever since then the belt has been culturally unified by the heritage of the Arab conquest, the religion of Islam. The eastern border of the belt can be set at the River Talas in Kazakhstan, where the Arabs defeated the Chinese in AD 751, but were unable to invade China.

Though the belt naturally lacks the regular censuses of China, there is abundant evidence of recurrent population crises, with their usual accompaniments, for instance of inflation, famine, violence and epidemics. In the great crisis of Babylonia (= Sumer + Akkad, see Figure 3.1) in the mid-second millennium BC, the price of barley tripled and the economy relapsed into barter. Towards the end of the Egyptian Old Kingdom (Table 2), the skeletal figures of starving peasants appear on a temple bas-relief. During the ensuing population crisis, an Egyptian writer produced a moving lament: ‘All is ruin. Blood is everywhere...’ In AD 1060, up to ten thousand people a day were dying of plague in Cairo.

The resulting massive fluctuations of population are attested by tax records and especially by archaeological surveys of density of settlement. Under the Sassanian kings of Persia (AD 226-637), the tax receipts of Khuzestan, in South-Western Iran, reached a figure twelve times as high as under the Achaemenid dynasty (539-331 BC). By the tenth century AD, the receipts had fallen to 40% of the Sassanian figure, and by the fourteenth century to 6%. In the Diyala Basin East of Baghdad, the number of settlements fell by more than 80% between the eighteenth and thirteenth centuries BC. The population cycles in these two regions are shown in Table 1. Notice the peaks, not in the present as in China, but under the Sassanians and the early Abbasid caliphs (AD 750-902). Grotesque underestimates of ancient and medieval populations in the belt have been published by those who ignore these kinds of evidence.

In AD 1377, the great Arab sociologist Ibn Khaldun of Tunis outlined the course of events in a typical region of the belt. Settlement led to high civilization. But then overpopulation set in, with its accompaniments of overtaxation, inflation, famine, violent revolts and anarchy. The weakened state would be conquered by a horde of barbarous sheep-herders from the adjacent wilderness, often fanatics. They would set up a new dynasty, which would become civilized, and the pattern would be repeated indefinitely. In his own Maghrib (North Africa West of Egypt), such herder dynasties included the Almoravids and Almohads. Elsewhere there were the Amorite and Chaldean dynasties of ancient Babylonia, the Hyksos in ancient Egypt, the Parthians and various Turks in later periods of Western Asia, and the Wahhabi Arabs in Arabia. But Ibn Khaldun noted that some invasions were enormously destructive. In the eleventh century AD, a roving Arab tribe, the Banu Hilal, destroyed forests, settlements and irrigation works all over the Maghrib, and the Mongols did much the same later in Western Asia. Ibn Khaldun used archeological evidence (the ruins that covered the region) to show that the Maghrib had had a populous and flourishing civilization before the Banu Hilal raid, and he also noted that the lands ravaged by these invaders had become completely arid desert.

The juxtaposition of settled areas and wilderness, that made all this possible, was already evident when civilization began in the region of Western Asia called by J.H. Breasted, in 1926, the Fertile Crescent, shown in Figure 1. South of this settled crescent lay wilderness with barbarian herders, and north of it mountain ranges with wild mountaineers, who also sometimes invaded and founded dynasties, those of the Guti and the Kassites. In the eighth to seventh centuries BC, the whole crescent was unified by the Assyrians, in a water-shed empire as horrible as that of the Ch’in in China. After this empire collapsed, Western Asia alternated between more civilized empires and a kaleidoscopic pattern of states with continually shifting rulers and frontiers. A simple table for the whole belt, such as we provided for China, is therefore impossible. But a few specimens will give a fair representative sample of cycles (not always in phase) throughout the belt. So, besides those of Table 1, we present the cycles of Egypt, in Table 2 and Figure 2. Population density was already so high in Ptolemaic Egypt (304-30 BC) that the curve for Egypt shows little rise between then and the twentieth century AD. Throughout the rest of the belt, there has been a fall, as in Table 1. The population of Iraq, for instance, has been estimated at thirty millions around AD 800; by the early twentieth century, it had shrunk to less than five millions.

Because of their climatic and geographic vulnerability, recurrent population crises in the settled regions of the belt caused increasing devastation of the environment: hence this unusual characteristic of their population graphs. One effect of the population crises was salinization. Already in Sumer (Figure 1), as in China, overpopulation led to competition for water between city-states on the Euphrates. As a result, the Tigris was also canalised, and eventually a large area of Sumer was irrigated from both rivers, as shown in Table 3. In this terrain, the resulting over-irrigation raised the water-table and brought salts into the surface soil, which became infertile, so that eventually Sumer was ruined and lost its political importance, as also shown in Table 3. Later salinization also affected Akkad, and by medieval times the regions of Table 1. In Khuzestan, in the ninth century AD, a desperate attempt was made to remove the saline surface crust, using massive slave labour imported from East Africa, but the only result was a devastating slave revolt.

Neglect and destruction of irrigation works during the crises led to excess deposits of silt. Deforestation by the invading herders, to create more pasture, and overgrazing by their sheep, led to massive erosion, silting, and formation of deserts. Throughout the belt, ancient records and the study of ancient wells show that rainfall has not diminished since at least Roman times, and a survey in Iraq in 1962 showed that all the deserts there were man-made. ‘In the rivers of my city’, wrote a Sumerian poet during a population crisis, ‘dust has gathered’. It is this accumulation of environmental damage that has reduced the carrying capacity, and hence the population density, of the whole belt.

The course of environmental devastation has been superbly well documented by A. Reifenberg for the Levant (modern Syria, Lebanon, Israel and Jordan). The region attained a peak of prosperity in Roman times, thanks to a number of very ingenious devices for catching, storing and distributing water. It was totally ruined by a succession of population crises in medieval times. Here we can only give three striking illustrations. Much of the region was still covered with forests in Roman times; less than 1% of the Levant is woodland today. As for erosion, since Roman times enough soil to make nearly four thousand square kilometres of good farmland has been washed off the western slopes of the Judaean hills, and the Roman theatre at Beit-Shan is covered by silt to the top seats. In the plain of Northern Syria around Qal’at Sim’an, by the mid-twentieth century AD, the ruins of forty-two ancient towns lay scattered among the fourteen villages still occupied, in a desert littered with ruined oil- and wine-presses; the hill of Testaccio, on the banks of the Tiber in Italy, is made up of the remains of huge broken jars that once contained the wine and oil imported to Rome from this now desolate region.

From the sixteenth to the nineteenth century AD, in the ravaged environment of the belt, the magnificent civilization of medieval Islam virtually disappeared. Islamic science, which had done wonders for centuries, was stifled by ignorant fanatics in power. The stresses of recurrent population crises and barbarian invasions produced what we have called stress culture, a complex of behavioural aberrations socially transmitted through the generations, whose most notable feature is the subjection of women. The same thing had happened in China, where the horrible practice of binding the feet of girl-children had become widespread by the tenth century AD. At about the same time, in the later tenth century, the seclusion of women was becoming customary in Islamic lands. This has nothing to do with religion. The Prophet Mahommed (AD c570-632) with an enlightenment far ahead of his time, did his utmost to promote equality between the sexes. The misogynistic remarks ascribed to him are known to be spurious. The pagan institution of the veil was first used under the horrible Assyrian regime, to distinguish free women (not to be assaulted in the street) from slave-women (fair game). In times of high Islamic civilization, as late as the ninth century AD, there were women who went unveiled, held salons, achieved distinction in politics and the arts, and even commanded troops.

In the nineteenth century AD, with a much reduced population, Islamic civilization began to revive. Printing, hitherto banned by the fanatics, spread in the belt, a printed press developed, and great Moslem reformers were active: Muhammad Abduh, who called for a revival of science, and Qasim Amin, who published a classical book on the emancipation of women. By the twentieth century, serious attempts were being made to restore ruined land and reconstruct the sophisticated water control technology of ancient and medieval times. But, as usual, population growth was soon outstripping the resulting increase in resources. By mid-century, the population of Iraq had doubled again, though still below the Abbasid level. Overpopulation now threatens the whole belt with widespread violence, a relapse into barbarism in the treatment of women, and renewed degradation of the environment. In Egypt, overpopulation and modern technology combined to produce the Aswan Dam, which is finally ruining the millennial prosperity of the Nile Valley, and the fisheries of the Eastern Mediterranean. Only immediate massive programmes of voluntary birth control can possibly avert further disasters in the great dry belt where civilization first began, and where it reached such glorious heights in earlier times.