The Mysterious 1,300-Year-Old Siberian Lake Fortress

It is one of the most mysterious archaeological sites in Russia – an ancient complex engulfing a small island in the centre of a remote lake in the mountains of southern Siberia. At first glance, it appears to be an ancient fortress, its perimeter of high walls constructed to keep out enemies.

However, others have proposed the 1,300-year-old structure may have been a summer palace, monastery, memorial complex, ritual centre, or astronomical observatory.

According to the Siberian Times, more than a century after its rediscovery, experts are no closer to understanding the secrets of these enigmatic ruins.

The archaeological site is known as Por Bajin (also spelt Por-Bazhyn), meaning ‘clay house’. It is located on an island in the middle of Tere-Khol Lake in Tuva, Siberia, just 20 miles (32 km) from the Mongolian border. 

First explored in 1891, the site was not excavated until 1957-1963. However, it was not until 2007-2008 that the first large-scale research was undertaken, carried out by the Por Bajin Cultural Foundation.

What they discovered presented a conundrum – the structure is located in a very remote place on the outskirts of what was the Uighur nomad empire, built with Chinese features, but with no sign of permanent habitation, and abandoned after only a short period of use.

Why was it built? How was it used? And why was it abandoned? These are the questions that have continued to both fascinate and frustrate experts ever since its discovery.

The Construction of Por Bajin

Believed to have been constructed in 757 AD, the ancient complex has outer walls that still rise to 40 feet (12 meters) in height and inner walls of 3-5 feet (1 – 1.5 meters), some still covered with lime plaster painted with horizontal red stripes. The main gate was discovered, opening into two successive courtyards connected by another gate.

The walls enclose an area of about seven acres containing the remains of more than 30 buildings but with a two-part central structure linked by a covered walkway, which once had a tiled roof and was supported by 36 wooden columns resting on stone bases.

Laser mapping of the site before the first major excavation in 2007 helped experts build a 3D model of what the complex might have looked like.

Only a small number of artifacts were ever recovered from the site – if it had been permanently inhabited one would expect to find a much greater number of items.  There was also no evidence of any kind of heating system, which would have made it impossible to stay there, at 2,300 meters above sea level, in winter conditions.

The main finds include clay tablets of human feet, faded coloured drawings, fragments of burnt wood, roof tiles, an iron dagger, a stone chalice, one silver earring, and iron construction nails. None of the artifacts provides a definitive answer as to why the structure was built, and how it was used.

Since the end of the 19th century, Por-Bajin has been linked to the Uighur Khaganate nomadic empire (744 – 840 AD), composed of nomadic Turkic-speaking people held together by forces of warriors on horseback. The empire spanned Mongolia and southern Siberia, however, the location of Por Bajin was still well away from settlements and trade routes.

Why would they build in such a remote location? Could it have been the site of a palace or a memorial for a ruler? The unique layout, more ornate than that of other Uighur fortresses of the period, has led some scholars to suggest that it might have had a ritual role.

Still, there are some other puzzling features. The architecture reflects a distinctive Chinese style, as evidenced by the use of Chinese building materials, such as certain types of roof tiles, and the use of Chinese construction methods.

The layout, with its axial planning, dominant central building, and residential quarters is consistent with styles seen in other Buddhist monasteries. But Por-Bajin shows no evidence of religious practice.

Why was it abandoned?

Not only has Por Bajin presented a mystery regarding its purpose, but archaeological evidence suggests it was abandoned after only a short period of use.

No evidence has been found to suggest the complex came under attack from an opposing force. Political changes in the region may offer one possible explanation, although nothing concrete has been presented to support this theory. 

According to Dmitriy Subetto, from the Department of Physical Geography RGPU, the structure may have been abandoned prior to completion due to the builders’ lack of familiarity with the permafrost.