The manufacture of textiles by pre-industrial societies was typically a demanding, multi-stage process, which involved obtaining fibres from an Animal or Plant, spinning it into a thread, and weaving it into a cloth, with dyes potentially being added at different stages to achieve colours or patterns. As such, textiles from archaeological sites can be important sources of information about the societies that produced them, giving evidence about trade routes and manufacturing techniques, as well as the social status, gender and age of the wearer.
Textiles from archaeological sites in Sudan have been studied since the early twentieth century, with material recovered from many sites in the mid Nile Valley. Wool and cotton are the most common fibres in these archaeological assemblages. Linen is also present, but in much lower quantities. Silk has never been produced in Sudan, so any silk discovered there can automatically be assumed to have been imported. Spinning of threads in Sudan was almost exclusively done in the S-direction (anticlockwise), while woven cloths were usually plain tabbies (a plain weave, with warp and weft threads crossing at right angles to form a criss-cross pattern) or weft-facing tabbies (cloths in which the warp is covered up by multiple, complimentary weft layers, enabling the building up of a pattern, which is typically angular in nature), often having bands or stripes in different shades.
However, determining the origin of fabrics from archaeological sites is complex, as plain and weft-facing tabbies are widely manufactured, and the textiles recovered from archaeological sites are typically very fragmentary. Even spinning direction is of limited use, as even in areas where the majority of spinning is done in one direction, the presence of local communities or even individual spinners doing the opposite cannot be excluded.
In a paper published in the Journal of African Archaeology on 11 August 2022, Magdalena Wozniak of the Department of African Studies at the University of Warsaw, and Zdzislaw Belka of the Isotope Research Unit at Adam Mickiewicz University, present the results of a study which used strontium isotope ratios to determine the origin of cotton and wool fragments from Late Antiquity and the Early Medieval Period recovered from archaeological sites in the Middle Nile Valley.
Strontium isotope ratios in water are strongly linked to local geology, and can be preserved in the tissues of Animals and Plants, making them a powerful tool in archaeology. Strontium isotopes have been used to track the movements of ancient Human and Animal groups, as well as tracing ancient trade routes by determining the origin of stone tools, glass, and textiles. This technique requires an understanding of the ratio of the isotopes strontium⁸⁷ and strontium⁸⁶ in the geology of the area, both locally and regionally. Armed with this it is possible to determine whether or not a material (in this case fabric) was manufactured locally, and in some cases where a non-local item originated from. Both Animals and Plants (the producers of wool and cotton) take up strontium from the environment in the ratios at which they are present, without any fractionation, with the strontium isotope ratios found in their tissues reflecting a mixture of that found in the bedrock and overlying soil as well as that from ground and surface water. However, the different ecologies of Animals and Plants mean that even when they live in the same area, they will have slightly different isotopic ratios.
Although obtaining an accurate strontium isotope ratio only requires about 100-150 mg of material, the desiccated and friable nature of most archaeological fabrics means that the process typically leads to the destruction of one or two square centimetres of fabric, so the choice of materials sacrificed must be made very carefully.
Wozniak and Belka used four textile samples from recent excavations near the fourth cataract, made available for the study by the Polish Academy of Sciences, as well as three samples provided by the Sudan National Museum and the National Corporation for Antiquities and Museums in Khartoum. All bar one of these was from a burial site, and all are of either wool or cotton. The sample was chosen to include samples which were presumed to be of both local manufacture and imported. None of the samples showed signs of decomposition or degradation, making it unlikely that they had had their isotope signatures overwritten by strontium from groundwater after being buried, something which can be a severe problem in wetter climates, but is less so in arid Nubia.
The first sample chosen, NT1, was a section of decorated warp-faced woollen fabric (woollen fabric in which the threads are packed together closely, hiding the weft) with roughly 14-16 warp threads and 8 weft threads per cm². This fragment was recovered from the bottom of a funerary chamber beneath Tumulus 24 in the El-Ar 1 cemetery, near the El-Ar village in Shamkhiya District. The El-Ar 1 cemetery has been dated to the 2-3rd centuries AD, with decorated fabrics being very rare there.
The second fragment used, NT2, is a piece of dark brown plain tabby woollen fabric, woven from S-spun threads, recovered from the El-Ar 4 Christian cemetery, and which could indicate a date anywhere between the sixth and fifteenth centuries AD. The fragment has 8-9 warp and 7 weft threads per cm², and comes from a section of shroud, which is in turn likely to have been a cloak or blanket used by the buried person and re-used as a shroud upon their death.
Sample NT6 is a course wool plain tabby, woven with 8 warp and 8 weft threads per cm², taken from the shroud of a naturally mummified body (i.e. preserved by burial in a dry environment, rather than Human intervention). The fragment is brown in colour, and very desiccated. The mummy was buried in a supine position, with hands resting on hips, which is indicative of a Christian burial, again implying the 6th-15th centuries AD.
Sample NT7 is a section of woollen kilim (woven tapestry rug). This has a dense weave with 7 warp threads and 32 weft threads per cm², and is woven in the slit-tapestry style, which creates the same pattern on both sides. The warp is a 2-ply z-spun (clockwise) cream wool, while the weft is single-ply z-spun wool in a variety of colours, including red, green, blue, orange, yellow and pink, giving a pattern of geometric and floral designs against a red background. The kilim was discovered in the town of Meinarti near the 2nd cataract in 1963, and has been dated to the 14th century AD.
Sample NT3 is a piece of weft-faced tabby cotton cloth from the El-Ar 4 Christian cemetery. The threads are S-spun and of a golden colour, with the weft threads thicker than the warp threads, and a thread-density of 11 warp threads and 19 weft threads per cm². This is a common, medium-quality cloth type at archaeological sites on the Middle Nile.
Sample NT4 is a fragment of cotton plain tabby from a Late Antique (2nd to 5th century AD) burial site at El-Ar. It is comprised of Z-spun white threads with traces of blue, green, and red pigments, probably a sign of resist dying (dying a finished fabric, while using wax or a similar substance to control which parts of the fabric the dye reaches), and a thread density of 22-24 threads per cm² for both warp and weft.
Sample NT5 comes from the shroud of a naturally mummified body of unknown providence in the collection of the National Corporation for Antiquities and Museums. The textile is desiccated, low density, cotton tabby with a thread count of 8 warps and 8-9 wefts per cm². The threads are Z-spun, and have a golden colour. This mummy was also preserved in a supine position, with hands on hips, indicating a Christian burial, between the 6th and 15th centuries AD.
Precambrian rocks of the Arabian-Nubian shield are widely exposed between the 2nd and 5th cataracts of the Nile. These exposures show a large variety of magmatic and metamorphic rocks, separated by suture zones with small occurrences of ophiolites and deep-water sedimentary rocks. To the west of the Nile Valley these are bordered by younger sedimentary rocks, predominantly Silurian sandstones. These rocks are overlain unconformably by the rocks of the Nubian Sandstone, which spreads across much of northern Africa, and includes a range of continental, esturine and marine sediments (predominantly sandstones), which in Sudan are predominantly of Cretaceous age. These Nubian Sandstone deposits have been mostly eroded away in the northeast of the country, exposing the underlying Precambrian basement, but extensive exposures are still present in the Bayuda Desert in the south, and the area to the west of the Nile. Tertiary Basalt rocks, which have intruded into these overlying strata, are exposed in the south of the country, around Abu Hamad. The floodplains of Nile Valley is also home to an extensive succession of Tertiary Sediments.
The volcanic rocks of the Precambrian basement of northern Sudan have strontium⁸⁷/strontium⁸⁶ ratios in the range 0.7024 to 0.7071, while the plutonic and metamorphic rocks of the basement have ratios in the range 0.7158 to 1.0039. The Cretaceous sediments of the Nubian Sandstone have strontium isotope ratios reflective of those of the basement rocks, with two clusters of values, around 0.7070 and 0.7160.
The alluvial sediments of the Desert Nile Valley are dominated by material derived from the Blue Nile and Atbara rivers, which drain from the Ethiopian Highlands, an area dominated by Cainozoic Volcanic rocks. These sediments have isotopic ratios in the range 0.7047 to 0.7076, a range which includes that of modern Nile water, at 0.7062. Nile muds dating from the end of the African Humid Period, about 45 000 years ago, show a strontium isotope ratio of 0.7052–0.7057, while those dating from between 1000 BC and 500 AD (i.e. between 3000 and 1500 years ago) show an isotope range of 0.7058–0.7076.
Samples NT1, NT2, and NT6 are all low-density woollen tabbies made from S-spun threads, technologically consistent with local manufacture. Sample NT1 contains cream and dark wool, used to make a pattern, while NT1 and NT6 are made entirely of undyed, dark wool. Lighter, cream-coloured wools are rare in the El-Ar assemblage, which may reflect the genetic structure of the local flocks (i.e. many brown Sheep and few cream Sheep). Alternatively, the local Sheep of the period may have been entirely brown, with cream wool being an imported commodity.
Sample NT7 is quite different from these, made up of coloured, Z-spun threads woven together using the split-tapestry technique to produce a decorative pattern, which is likely to indicate that this was an imported item. Furthermore, furthermore, the red dye used on some of the wool appears to have been treated with a lac dye, derived from the Scale Insect, Laccifer lacca, which is found in South and Southeast Asia and South China, but quite alien to the Nubia, where red dyes were traditionally derived from the Madder Plant. This apparently non-local item dates from the 14th century, a time when Meinarti was occupied by the Beni Ikrima, a nomadic group from the Maghreb region.
All four wool samples yielded strontium isotopic ratios within the range 0.7075 to 0.7084. In order to better compare these to the local environment, Wozniak and Belka also obtained strontium isotope ratios from Sheep and/or Goat remains (the two are hard to tell apart) from several archaeological sites between the 2nd and 4th cataracts. All of these remains are known to be older than the wool samples, dating to between 2500 and 500 BC, and gave isotopic ratios in the range 0.7068 to 0.7082 (one set of remains gave a much higher reading, of 0.7109, though this is likely to indicate that the Animal was of non-local origin).
Three of the investigated wool samples, NT1, NT6, and NT7, had isotopic ratios entirely consistent with archaeologically derived Sheep/Goat remains from the region, and the fourth, NT2, fell only slightly outside this range, and still within the range of Cattle and Human remains from the Desert Nile Valley.
Of the three cotton samples, only one, NT3, was made of a yarn spun in an anticlockwise, S-direction, typical of local manufacture in Nubia or Egypt. The other two, NT4 and NT5, were spun in a clockwise, Z-direction, which may indicate non-local manufacture. One of these, NT4, also shows signs of a resist-dying technique, not known in Nubia in the 2nd-5th centuries AD, but common in textiles from India during this period.
These three samples show a narrow isotope ratio range, from 0.7084 to 0.7086, which makes it likely that they were derived from crops grown within a limited geographical area. As a crop, cotton requires a rather specific set of conditions, with a hot dry climate, and large amounts of available water for several months of the year. This can be provided in the Nile Valley between the confluence of the White and Blue Niles and the 2nd cataract, although water and plants derived from this region show isotope ratios below 0.7075, ruling this region out as an origin point for the cotton in the study. Cotton is also grown around the Nile Delta, and ancient cotton fibres and seeds have been recovered from other sites along the Lower Nile, suggesting that cotton may have once been grown more widely. Strontium isotopic signatures are not available for sediments from all of these areas, but the isotopic signature of the Nile water, at about 0.7069, makes it unlikely that any of these floodplains have an isotopic ratio above about 0.7075. Similarly, the sediments of the Atabara and Blue Nile valleys have average isotope ratios between 0.7041 and 0.7060. All of these locations therefore seem unlikely as a point of origin for the cotton used to make the textiles included in the study.
However, cotton grown in the Western Desert of lower Nubia typically has an isotopic value of about 0.7085, and limestones from the Western Desert of Egypt can have strontium isotope signatures in the range 0.7077 to 0.7078. Cotton is known to have been grown in this region in the 2nd-3rd centuries AD, using irrigation systems which drew upon shallow groundwater reservoirs, supplied by rainwater that had filtered through Eocene carbonates, which could conceivably produce a cotton with a strontium isotopic signature of about 0.7085.
Cotton is also known to have been produced in Meroe, on the lower White Nile to the south of Khartoum, during the Roman period, although both the water and plants from this region tend to have a higher isotopic ratio than the cotton from the study, excluding this region as a point of origin.
There is strong evidence for the production of cotton in Egypt and Sudan in Roman and later times, but the possibility of material also being imported from further afield should not be ruled out. Cotton was widely cultivated in India and on the Arabian Peninsula during antiquity, and both raw cotton and finished textiles could easily have been imported to Nubia via the Red Sea. Cotton seeds and textiles excavated at Mleiha in the modern United Arab Emirates have been shown to have originated from western India by their strontium isotope ratios. Unfortunately, strontium isotope information is only available for a few locations on the Arabian Peninsula or from India or Pakistan. However, several regions would be compatible with the isotope signatures obtained from the cotton samples, including the lower Indus River Basin, in India and Pakistan, the Kathijawar Peninsula on the west coast of India, the area covered by modern Kuwait, and the Oman Peninsula.
The isotope signatures obtained from the wool samples from archaeological sites in the Nubian Nile Valley all support a local origin. This is also supported by the technological features of three of the samples, NT1, NT2, and NT6, but not the fourth, NT7. This sample, a kilim rug from 14th century Meinarti, appears to have been made with a technology entirely alien to this part of the Nile Valley. However, it also dates from a time when the city of Meinarti was occupied by an alien group, the Beni Ikrima, who originated from the Maghreb region. Since the Maghreb has a geology with similar strontium isotopic ratios to that of northern Sudan, it is possible that the kilim was brought to the area by the Beni Ikrima from their homeland. However, it is also possible that the kilim was made locally by Beni Ikrima craftspeople from wool obtained from local, Nubian, flocks. Wozniak and Belka conclude that, given the available isotopic evidence, the more likely scenario is that the kilim was made locally, contrary to previous expectations.
In contrast, the isotopic signature of the cotton samples examined fits poorly with an origin in the Nile Valley. The samples all have very similar isotopic signatures, which seems to imply a common origin, although this is at odds with the different spinning techniques used. One of the samples, NT3, has an isotopic signature that fits well with the Dakhla/Kharga oasis in the Egyptian Western Desert, which has previously been identified as a possible site of ancient cotton cultivation. This piece also shows a technology consistent with production in the Nile Valley, notably an S-spun yarn. Importing cotton textiles from an oasis in the Western Desert would only make sense if local, Nubian, production was failing to meet demand. The frequency of cotton fabrics from archaeological sites in Nubia has been observed to have dropped during the Late Antique and Early Medieval periods, so this is not implausible, although an alternative explanation could be that the deceased person for whom this item was used as a shroud had travelled during their lifetime, either moving from the Western Desert to Nubia and bringing the cloth with them, or at some point visiting the Western Desert and obtaining the item there.
Sample NT4, on the other hand, appears much more likely to be of Indian origin, where a block printing technique using resist dying was common at this time. The isotopic signature of this sample matches that of the Kathijawar Peninsula on the west coast of India, leading Wozniak and Belka to conclude that this item was most likely imported from India. This adds evidence to the inclusion of the area around the 4th cataract into long distance trade networks, something previously indicated by the discovery of glass beads of foreign manufacture in the region.
Sample NT5 also appears to be non-local in origin, with a Z-spinning technique having been used, and a non-local isotopic signature. However, there is insufficient evidence to give a precise origin for this fragment at this time, with possible points of origin including Indus River basin in Pakistan, the west coast of India, Kuwait, and the Oman Peninsula.
Although Wozniak and Belka were not able to determine the point of origin of all the fabrics in the study, their study shows the potential for determining the origin of ancient fabrics using strontium isotope ratios. The development of a wider data set of strontium isotope values for textiles could add to the information obtained by examining the technological aspects of textile-making, to provide a better understanding of the manufacture of and trade in cloth in the ancient world.
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