The Rubassky architectural complex (Eastern Caucasus) of the VIII century : new data on excavations in 2023

Gmirya Lyudmila Borisovna ORCID: 0000-0002-1298-7485 Doctor of History Leading Researcher; Institute of History, Archeology and Ethnography; Dagestan Federal Research Center of the Russian Academy of Sciences 367030, Russia, Republic of Dagestan, Makhachkala, Yaragskogo str., 75, room 505 b ljuma78@yandex.ru

The Rubassky architectural complex was opened in 2014 in the lower reaches of the Rubas River, 20 km south of Derbent ^{[2, pp. 108-111]}; ^{[3, pp. 139-161]}. His research was conducted during 7 field seasons (2014, 2016-2018, 2020, 2022-2023) by the Institute of History, Archeology and Ethnography of the Russian Academy of Sciences. Excavations revealed 6 buildings of different types: 1) the construction of an arched structure; 2) wall No. 1; 3) main wall No. 2; 4) wall No. 3; 5) structure No. 6 of a stepped structure; 6) structure No. 5 in the form of a platform with a surface slope of 22.50 (Fig. 1). Each structure has an individual design, a kind of set the used building materials and targeted orientation, as well as a special place in the complex associated with its functions. The primary interpretation of the engineering facility identified in the Rubas River Valley was defined as a military-technical defensive facility ^[2]; ^[3]; ^[4]; ^[6]; ^[8]; ^[9]; ^[10]; ^[14]. Chronologically, it was assigned to the middle of the VI century, given the similarity of the construction technology with the Derbent defensive complex. However, the analysis of data (archaeological and source materials) showed that the Rubassky architectural complex has a highly specific function due to the need to supply irrigation water to the city of Derbent during the late 8th century. The complex of construction facilities on the Rubas River, identified by research, is defined as a hydro-technical facility (hydroelectric unit) ^[7].

3 identified structures were fully investigated - wall No. 1, arched structure and main wall No. 2 (Fig. 1). The design features of these buildings were revealed, their functional purpose was determined, and the nature of the connection with other buildings was established ^{[10, pp. 465-482]}.

In 2023, excavations of 3 architectural structures of the Rubassky building complex were continued, the full shape and dimensions of which have not been established: structure No. 6 of a stepped structure; wall No. 3; structure No. 5 in the form of a platform (Fig. 1).

1. Excavation of building No. 6

(Northern extension to the main wall No. 2)

The purpose of the excavation of this structure was to determine its full size and functional purpose. According to the results of excavations in 2022, the northern section of structure No. 6 went under the northern side of the excavation. Its length was 6 m. In 2023, an area of 18 sq. m was cut to the northern side of the excavation - the length in the C-Y direction was 3 m, along the B-Z line was 6 m (Fig. 2, 3). Excavations at this site revealed the final section of structure No. 6 of a stepped structure with a length of 1.8 m.

In 2023, 7 rows of masonry were opened. The upper level of the masonry of this structure ended in a large massive block (length 1.2 m.), the northern end of which was rounded by brushing (Fig. 2-3). The total length of the upper level of the structure of the stepped structure No. 6 was 8.6 m (Fig. 2).

The second row of masonry had a length of 8.8 m, it was 0.2 m longer than the first row (Fig. 2, 3). The design feature of the final section of structure No. 6 consisted in the projection to the north of all subsequent rows of masonry (3-7) in relation to the first row by 0.8 m (Fig. 2, 3). Probably, this technique enhanced the stability and strength of the final section of this structure.

The maximum length of the structure No. 6 of the stepped structure according to the results of excavations in 2023 was 9.4 m (Fig. 2). Its functional purpose has not yet been established. But given the presence in the structure of 6 blocks of considerable length (1.8-2.2 m.), installed along the width of the structure (B-Z), it can be concluded that this structure carried a heavy load.

It should also be noted that the blocks of all rows of masonry structures of the stepped structure were fastened with brackets (oblong recesses with a total length of 0.26 m were preserved) (Fig. 2, 3). In the masonry of this site there are 2 blocks of considerable length – 2.0 m and 1.9 m. with the thickness of the latter 0.4 m (Fig. 2).

The height of the final section of the structure of the stepped structure No. 6 was 1.6 m. The thickness of the facade blocks was in the range of 0.2-0.28 m. One of the peripheral (internal) blocks had a thickness of 0.5 m.

2. Excavation of Wall No. 3

In 2023, excavations of the eastern section of Wall No. 3, identified in 2022, were continued. Excavations of Wall No. 3 began in 2014. Of all the open structures of the Rubassky architectural complex, this building is characterized by the greatest complexity. This is due not only to its design, but also to the state of preservation. Long-term excavations of this site have shown that it is structurally connected to the main wall No. 2. But for a long time it was not possible to determine the purpose and objectives of connecting these two objects into a single complex. In the course of the research, it turned out that not two, but three construction sites were connected into a single bundle - wall No. 2, wall No. 3 and the construction of a stepped fan-shaped structure (Fig. 1).

The difficulty in determining the architect's intention was the complete destruction of this site by the land user in which this connection was carried out. It took several years of careful excavation to figure out the design of this section of the complex, but so far not everything has been possible. It is necessary to investigate a 3.0 m deep excavation with a diameter of 7.0 m, which was formed in 2014 at the site of unauthorized excavation of large blocks.

The first information about the monumental architectural structure on the Rubas River near the village of Kommuna was received from the director of the Gadzhi-Kurban school, Jalilovich Bayrambekov, in February 2014. For many years I was familiar with him and his family during the excavations of the Palace-Syrt burial mound of the IV-V centuries in 2006-2016. He provided the necessary assistance to our expedition and was interested in all the news himself. He graduated from the Pyatigorsk Institute of Foreign Languages, was a translator in Cambodia, was seriously injured, returned to his native village of the Commune of the Derbent district of the RD, where he taught French at school, later headed the school. His last position was head of the SS administration. Rubas and the Commune. A year ago, he died at the hands of an unbalanced man. He had 3 children, 9 grandchildren and elderly parents.

Gadji-Kurban treated the archaeological site on the Rubas River with great trepidation. It was he who informed me that on the banks of the Rubas River, near the village of Commune, a local resident discovered a monumental structure of large stone blocks with a length of 1.0-1.5 m. The land user pulled stone blocks from the masonry of the structure with an excavator bucket and transported them to his house, where he sawed into small pieces, planning to build a new house. There has never been any data on the presence of any monumental buildings in this area before.

The barbaric destruction of this unique architectural monument was stopped in 2014. The stone blocks extracted by the land user were seized and transferred to the Rubas school for storage. At the site of the destruction of the archaeological site, as noted, a pit with a depth of 3.0 m and a diameter of 7.0 m was formed (Fig. 1).

In August 2014, exploratory excavations were carried out both within the northern part of the pit and on the territory of the land plot adjacent to it from the west.

Two architectural objects were identified in the adjacent territory (excavation 1) - the construction of an arched structure and a section of wall No. 1 attached to it from the north.

On the northern slope of the excavation, a small section of the eastern facade of the main wall No. 2 and a section of the structure built into it, as it turned out later, of a stepped fan-shaped structure, were cleaned. Initially, this section was perceived as a section of wall No. 3, oriented in the Z-V direction. But later the full shape of this object was revealed, which had a stepped structure and a fan structure. This object was originally identified as Wall No. 3, built into the eastern facade of Wall No. 2. But it was not possible to identify its exact functional purpose due to the unusual design and the almost completely lost western section of this structure.

However, the upper level of this structure attracted attention (excavations in 2018, 2020), which, unlike other levels, had a linear shape oriented in the direction of the South-St. The final interpretation of Wall No. 3 was defined as a linear structure with a fan-shaped structure built into its northern facade.

The western section of this stepped structure has not been preserved. It was probably connected to the opposite section of the eastern facade of wall No. 2, which also had a stepped structure.

In the eastern facade of wall No. 2, on its lower level, there is a large block installed in an unconventional way - with the corner part facing out. It appears that the fan-shaped structure built into the northern facade of wall No. 3 was apparently connected by a semicircular line to the southern section of the eastern facade of wall No. 2 at the installation site of the corner block (Fig. 1).

A stepped fan-shaped structure connected the angular connection of two multidirectional walls of a massive structure - wall No. 2 and wall No. 3. Given the massiveness of the fan-shaped structure, it was designed for significant loads.

In 2023, the study of the eastern section of wall No. 3 was continued, the upper level of the masonry of which was opened in 2022.

According to the results of the excavations in 2023, its length within the cutting No. 23 was 5.0 m. It was oriented in the direction of the South-South. The complete structure of this structure has been preserved only on the eastern segment. Its maximum length along the SV-SW line is 3.0 m (Fig. 1; 4). In this area, the northern and southern facades of wall No. 3 and the internal blockage of crushed stone were revealed (Fig. 1; 4-7). The thickness of Wall No. 3 is 2.2 m (Fig. 4). Wall No. 3 continues to the northeast (Fig. 1; 4-6).

The identified facades of wall No. 3 are constructed of massive stone blocks according to the "poke-spoon" system. One of the blocks is mounted with the front surface facing out onto the edge, the other with the side surface facing out (Fig. 5-7). There are 5 masonry blocks on the southern facade of wall No. 3 (Fig. 6). The length of the lower spoon block is 1.4 m, the thickness of the poke blocks is 0.2 m. On the northern facade, 2 spoon blocks (length 1.0; 1.1 m) and 2 poke blocks (Fig. 7) have been preserved on the lower level. On the upper level there are 3 poke blocks limiting the inner lining of small stone (Fig. 4). The height of the preserved facades of wall No. 3 is 1.4-1.5 m (Fig. 7).

Wall No. 3 continues to the northeast, its structure goes under the eastern and partially northern sides of the cutting No. 23 (Fig. 1; 4-6). Further excavations of Wall No. 3 are needed.

3. Excavation of structure No. 5 in the form of a platform

In 2023, further research was continued on the southern section of structure No. 5 in the form of a platform with a surface slope to the east of 22.5 °. The purpose of the excavations was to determine the full shape, construction and functional purpose of this unusual structure. Analogues of this structure have not yet been established.

Structure No. 5 in the form of a platform has a rectangular shape. According to the results of research in 2022, its maximum length was revealed within 8.0 m (east side), the length of its facade was 6.2 m. The facade includes 6 horizontal rows of masonry from massive rectangular blocks (Fig. 8). The height of the facade of this structure is open to the level of 1.94 m.

The full shape of this structure within the excavations has not yet been revealed. The eastern side of this structure is located under the eastern side of the excavation.

The peculiarity of its design consists not only in its unusual shape (a large rectangular object with a height of about 2.0 m), but also in the significant slope of the surface. The upper level of this structure has a slope to the east of 22.50.

There is another feature of this structure. The stone blocks of all the studied structures of the Rubassky architectural complex have a careful surface treatment. However, the blocks of the upper level of building No. 5 have flaws, recesses, and irregularities. It is assumed that this object was subjected to prolonged exposure to falling water flows.

Excavations in 2022 also revealed that the blocks of the western facade of structure No. 5, located in the immediate vicinity of the southern side of the excavation, were in a position with a sharp rise in the southern ends relative to the northern ends (Fig. 8-9). The difference in levels was between 6-10 cm. It was assumed that the violation of the horizontal installation of the blocks of the structure in the form of a platform was caused by the presence of a rock outlet. However, research in 2023 revealed a number of circumstances that significantly affected the safety of this unique object.

In 2023, the excavation of structure No. 5 in the form of a platform was continued. The research took place on the territory of the cutting No. 25 with a length of 4.0 m in the C-Y and 8.0 m in the C-Z direction (Fig. 1). This site is located south of the excavation site in 2022, in close proximity to the left bank of the Rubas River.

The purpose of the 2023 excavations at this site was mainly to identify the full extent of this archaeological site in the C-Y direction. The issue of the possible location of the southern section of structure No. 5 in the riverbed of the Rubas River was particularly acute. Since 2014, an accumulation of large stone blocks and their fragments, similar in shape to the building materials of the Rubass architectural complex, has been recorded at the bottom of the river in this area.

However, at the lower level of the excavation in 2023, a significant number of stone blocks of different preservation were discovered - whole shapes, large and small fragments located throughout the territory of the cutting No. 25 in several layers without any system (Fig. 1; 8-9). There was a whole large block 2.2 m long, 0.2 m thick, located in the position on the edge in the C-Y direction (Fig. 1; 8-9). This block was probably removed from the masonry of the facade of building No. 5 for the purpose of transporting it, but this could not be done.

On many stone blocks removed from building No. 5, even on the wreckage, there were recesses for installing staples to fasten them in the structure of the structure (Fig. 9). This indicates that these blocks were extracted from an undisturbed structure.

According to the results of the excavations in 2023, the length of the preserved section of structure No. 5 in the form of a platform with a surface slope to the east within the cutting No. 25 measuring 4×8 m (32 sq. m. m) was 1.3 m (Fig. 8-9). The rest of the southern section of building No. 5 was removed from its construction (Fig. 8). In the eastern side of the cutting (length 4.0 m) at the lower level there were small fragments of blocks.

Fragments of stone blocks of different sizes were recorded on the territory of the cutting No. 25 with a length of 8.0 m along the B-Z line. In most cases, the fragments of stones lay in several layers over the entire area of the cutting No. 25 (4.0×8.0 m.). Some of the fragments of blocks were at an angle to the surface of the excavation, going deep into the ground (Fig. 8-9). There may be underlying levels of this structure.

Rocky outcrops with traces of horizontal undergrowth were also identified in the studied area.

The destruction of this section of structure No. 5 in the form of a platform is not yet explicable. There are two possible reasons - natural and human factors. The natural factor can be associated with a severe flood, the flow of which was directed from the Rubas river to this object. The human factor was probably manifested in the purposeful dismantling of the structure in the form of a platform for the extraction of building material. It is also possible that structure No. 5 had the function of a dam blocking the riverbed of the Rubas River in order to collect water into the reservoir.

Written sources contain information about the presence of a complex of hydraulic structures on the Rubas River, which provided river water supply to the canal for watering gardens, vegetable gardens, vineyards and mills in the vicinity of Derbent. The construction of this unique facility is associated with the activities of the Arab Caliph Harun al-Rashid (786-809), carried out during his stay in Derbent (790-797).

The local historical chronicle "Derbent-name" notes: "Harun Rashid, having arrived in Derbent himself, did a lot to improve [the city]. He brought irrigation ditches with water to Derbent, built mills, and ordered a lot of gardens and vegetable gardens to be laid out. He gave the order to take [funds] for the repair of irrigation ditches from the income from agriculture and gardens" ^{[11, p. 324]}.

In the historical work "Asari-Dagestan. Historical information about Dagestan" by Hasan Alkadari (1834-1910) It is specifically indicated from which source the water came to Derbent and the structure through which it was transported is indicated: "In 173, in the year 790 of the Christian faith, Harun ar-Rashid sent a ruler named Khuzeima ben-Hazim to Derbent with a detachment of up to two thousand soldiers. This new ruler of Khuzeim, having forced to dig a ditch from the Rubasa River, conducted water to the Derbent lands, allowed gardens, vegetable gardens, arable land to be planted below the ditch and mills to be built" ^{[1, p. 28]}.

In E. I. Kozubsky's extensive work "The History of the city of Derbent" (1906), information about the fact of the construction of the Rubas-Derbent irrigation facility is presented in the author's presentation based on written sources: "Harun himself came to this city. He built fortifications on the Rubas River and ordered it to be dammed and its water carried through the surroundings of Derbent, which flooded a large area of the steppe, turning it into a fertile oasis. Having destroyed part of the fortress walls and repaired the rest, he ordered to plant gardens, vegetable gardens and vineyards, supplying them with water through water pipes, setting up mills on the latter, the proceeds of which he donated to the benefit of the poor of the city" ^{[12, p. 31]}.

Having named the specific facts of measures for the construction of a complex hydraulic engineering facility on the Rubas River, gleaned from written sources, E. I. Kozubsky indicated a number of analytical data that complement information about the design of this technical facility (hydroelectric facility) and the positive effect of its use. E. I. Kozubsky indicates that "fortifications" were erected on the Rubas River and A "dam", i.e. a dam through which a reservoir was formed. The effect of using this technical facility consisted not only in the transfer of river water for the needs of residents of Derbent. E. I. Kozubsky emphasizes that the population of "a large expanse of steppe also benefited, turning it into a fertile oasis" ^{[12, p. 31]}.

Some signs of the presence of indicators of a hydroelectric facility are installed on this monument – the construction of an arched structure; wall No. 3; the western facade of mill No. 2; powerful pebble deposits in the space between wall No. 1 and the western facade of wall No. 2 (Fig. 1:1,4,3), but further targeted research on this topic is required. It is necessary to fully investigate two structures: wall No. 3 and building No. 5 in the form of a platform (Fig. 1).

Of particular importance are specialized studies to determine the location of the reservoir for collecting irrigation water from the Rubas River and the route of the Rubas-Derbent canal, along which it was distilled.

Currently, 2 channels supply water to the cities of Derbent-Rubassky and Samur-Derbentsky. The Rubassky Canal originates on the left bank of the Rubas River, at a distance of about 1 km west of the archaeological hydrotechnical site. The modern complex includes a small reservoir, a dam with locks and a canal bed. The initial section of the canal is approx. 1 km adjoins the northern section of the Palasa Syrt hill. But when entering the plain, the direction of the channel was changed along the South-S line towards Derbent. It is possible that the ancient Rubas-Derbent canal passed through this channel. Residents of the village of Commune use this canal to water their gardens and vegetable gardens. The Samur-Derbent Canal is located to the west of the Rubassky Canal, its channel is parallel to it. It is more powerful and equipped with modern equipment.

Considering that Derbent dates back 2.5 thousand years, the idea of the Arab Caliph Harun al-Rashid about the need to build a canal from the Rubas river to Derbent at the end of the VIII century. It is still relevant, although it is based on the experience of the population of the Middle East of the ancient era ^{[13, pp. 179-181]}.

Fig. 1. Rubassky architectural complex. 1 – arched structure; 2 – wall No. 1; 3 – wall No. 2; 4 – wall No. 3; 5 – structure No. 5 in the form of a platform; 6 – structure No. 6 of a stepped structure. View from the east. Aerial photography in 2023

Fig. 2. Rubassky architectural complex. Structure No. 6 of a stepped structure. View from the east. Photo 2023

Fig.3. Rubassky architectural complex. Structure No. 6 of a stepped structure. View from the north. Photo 2023

Fig. 4. Rubassky architectural complex. Wall No. 3. View from the northeast.

Photo 2023

Fig. 5. Rubassky architectural complex. Wall No. 3. View from the southwest.

Photo 2023

Fig.6. Rubassky architectural complex. Wall No. 3. View from the southwest. Photo 2023

Fig.7. Rubassky architectural complex. Wall No. 3. View from the north. Photo 2023.

Fig.8. Rubassky architectural complex. Structure No. 5 in the form of a platform with an inclination of 22.5 ° . View from the northwest. Photo 2023

Fig.9. Rubassky architectural complex. Structure No. 5 in the form of a platform with an inclination of 22.5 °. View from the north. Photo 2023