There are only three essential structural systems in architecture: the post and beam trabeated, the
arch and its extensions arcuated, and those that employ stretched filaments and membranes tensile.
Because durable tensile materials like steel and reinforced concrete were not developed until after
1865, and synthetic membranes, like fiberglass-Teflon laminate and Kevlar, until more than a century
later, tensile technology was limited to buildings not consideredproper architecture. But despite the
denial of means, the method of creating them has been understood, refined, and applied from ancient
times. Purest among such applications are the tents of the Bedouin. Their origins are lost, but they are
indeed architectural feats for their structural economy, functionality, and environmental sustainability.
The nomadic Arabs known as Bedouin badawi, fordesert dwellers inhabited Arabia from
sometime in the second millennium b.c. With the expansion of Islam in the seventh century a.d., they
spread into the Syrian and Egyptian deserts and invaded northern Africa, where their flocks, allowed
to overgraze, soon turned much of the coastal pasture into semidesert. The Bedouin, who now comprise about 10 percent of the population of the Middle East, continue to herd camels, sheep, goats, and sometimes cattle. Their patterns of migration depend on availability of pasture: in winter, if there is rain, they move farther into the desert in summer, they locate near assured water supplies and build simple mud-and-stone temporary houses. While on the move, the Bedouin live in a beit al-shar house of hair. The dwelling, little changed for about 4,000 years, consists of short wooden posts supporting a framework of tightly stretched goat-hair ropes, over which a loosely woven goat-hair cloth membrane falaif is stretched to serve as walls and roof.
The goat-hair yarn is spun on a drop spindle by the older women and woven into cloth strips on a horizontal loom. The breadth of the strips approximates the ancient cubit about 20 inches or 50 centimeters they vary in length from 23 to 65 feet 7 to 20 meters, depending on the size of the tent for which they are made. Because the women work only inspare time, even short strips of cloth may take several months to produce. The portable loom allows any unfinished work to be rolled up when the group moves on. The finished strips are sewn together with black goat-hair thread to make up a single roof membrane. That is a social occasion, with women working together. The goat hairs natural color, usually black, is retained, although sometimes the addition of sheeps wool yields a streaked cloth. The black fabric absorbs heat, but it also provides deep shade, so that temperatures inside can be considerably lower than outside. The coarse weave allows heat to disperse, and the covering provides good insulation in the cold desert night. When it rains, the loosely woven fabric swells, stopping most leaks. A tent cloth lasts an average of five years, and its maintenance and replacement depend upon a renewable resource, as they have for centuries.
When the Bedouin make camp, the leader of the band directs the women in pitching the tent. Before the poles are raised, the roof is spread on the ground, with one of its long sides facing windward, and stretched by tightening lines attached to pegs. Once it has been lifted on the pole and rope frame, the goat-hair flaps that form the wallslong enough to enclose the entire tent at nightare hung and pegged down, with the entrance facing away from the prevailing wind. The low profile of the roof and very long guy ropes are designed to maximize wind resistance.
Traditionally, brightly decorated curtains divide the interior. The mens area, always at the end toward Mecca, also incorporates the majlis, where guests are received around a hearth. The private family area mahram, or womens section, is much larger and barred to all men except the head of the family. The third space is the kitchen. Of necessity for a nomadic lifestyle, furnishings are sparse. Carpets and mattresses cover the desert floor pillows stacked around a camel saddle may provide seating for guests.
The Tuaregs, descendants of the Berbers, whom the Arabs displaced from North African coastal regions, also live in tents. About 800,000 strong, the seven major Tuareg confederations inhabit an area from the western Sahara to western Sudan. Although some have permanent settlements, most prefer small nomadic groups. Believing thathouses are the graves of the living, they set up rectangular tents about 10 feet 3 meters long and 10 to 15 feet 3 to 4.6 meters wide, covered with up to forty tanned goatskins, dyed red and sewn together, or mats of palm fiber. In this matriarchal society, when a woman marries, her family makes a tent for her, and it remains her property. In about two hours, she can put her household on pack animals, ready to move on.
Two other examples will demonstrate that not all transportable houses are tensile structures. The nomadic lifestyle of some Amerindian tribes was constrained by the migration of the great buffalo herds. Their houses needed to be strong enough to withstand the prairie winds while lending themselves to easy dismantling, carrying, and reerection. Possibly derived from the Inuits Arctic summer dwellings, the tepee was adopted about two hundred years ago as the year-round house of the Plains nations. A conical skeleton frame of up to thirty wooden poles was lashed together near the top and covered with a fitted membrane of tanned buffalo hides. Although it was transportable, it did not share all the tensile characteristics of the Bedouin tent. The same is true of the ger or yurt, the traditional house of Mongolian
herdspeople, still in use all year-round. Its self-supporting framed structurea cylinder roofed with a
domeapplies a dynamic arrangement, refined over centuries, of leather-lashed saplings, a roof ring,
and tensioning bands. The covering, traditionally felt, is secured with ropes. The ger can be
dismantled and carried by pack animals, although sometimes it is transported intact on a wagon.
Many Middle Eastern governments are attempting to impose a permanent sedentary lifestyle on the
Bedouin, Modernization, if not altogether desirable, is probably inevitable. Trucks are displacing
camels as the principal means of transportation some camps have refrigerators and television sets
powered by portable generators whose noise disturbs the quiet of the desert. Coffee is brewed for
guests on gas stoves rather than the traditional hearth, andoff-the-hook canvas tents are appearing
among thehouses of hair.