西伯利亞考古發現中國唐代寧國公主的行宮,在俄羅斯西伯利亞南部圖瓦共和國昆古爾圖克小鎮附近的鐵列霍勒（Tere-Khol）湖中有一座古城遺址，遺址名為“博爾巴任”(Por-Bajin)，屬唐式建築，應為回鶻人所建。但回鶻人所留的文字資料極少，博爾巴任古城遺址被發現於19世紀末，蘇聯考古人員從20世紀五六十年代開始對其進行了多次考古挖掘。這座古城的身世到現在都無法準確考證，在考古史上依然是一個謎，也是俄羅斯最神秘的遺址。這處古城堡遺址佔地約4公頃，距離俄蒙邊境數十公里。考古學家們在此發現了方形建築物地基、與建築物正面相連的成對樓梯、立式梁結構、支撐屋頂的雕花頂梁結構、陶制瓦片等具有中國唐代建築特色的遺迹。此外，考古人員還發現了繪有雕花圖案的赤陶浮雕等，這種吉祥圖案在中國唐代古迹中較為常見。
考古專家根據以上發現推測，該城堡並非尋常大戶人家宅院，可能是遠嫁回鶻的
由於當時的回鶻可汗曾幫助唐朝平定“安史之亂”，唐肅宗將女兒寧國公主許配給其為妻。寧國公主及其隨從於公元758年抵達回鶻都城(位於今蒙古國境內)，該地距離昆古爾圖克僅有2天路程。
遺址還發現有地震及燃燒過的痕迹，“博爾巴任”可能曾被地震引發的火災所損毀。此外，當地冬季非常寒冷，“博爾巴任”沒有發現取暖系統，顯示此遺址使用的時間短，可能完工沒多久就廢棄了。由於此遺址使用的時間短，城內屋小獨棟格局又相似，像是高僧的住所，因此，也有學者推測“博爾巴任”可能是回鶻的牟羽可汗興建的摩尼教寺院。摩尼教是回鶻人（維吾爾族）的官方宗教，維吾爾統治者尋求與中原的強有力的政治關係，聯姻便是其中一種政治手段。婚姻聯繫和共同的宗教信仰，似乎都導致了中國建築概念和建築者湧入回鶻帝國。
The ancient fortress that has historians - and Putin - baffled: Nobody knows why spectacular 1,300-year-old Siberian island fort was built... or why it was abandoned
Por-Bajin was discovered a century ago and is still a mystery for experts,The 3.5 hectare site is located in a Siberian lake near the Mongolian border
The unexplained site is estimated to have been built between 744-840 AD.
At first glance the rectangular island of Por-Bajin looks like a foreboding fortress or prison, with its regular structure and ruined sections.
But it is unknown for certain what the rectangular island and its labyrinthine ruins, located in a lake in deepest Siberia, was actually used for when it was built 1,300 years ago.
Historians and scientists are divided, but some experts believe the isolated area may have been built to attract people instead imprisoning them, and suggest it was a summer palace, monastery, or an astronomical observatory.
The name Por-Bajin translates as clay house in the Tuvan language, and the island sits between the Sayan and Altai ranges, about 3,800km from Moscow near the Mongolian border.
The location was first discovered in 1891, and the purpose of island has still not been explained over a century later.
More in-depth research took place in 2007 with archaeologists discovering clay tablets of human feet, faded coloured drawings on the plaster of the walls, giant gates and fragments of burnt wood.
Experts say the island was built during the period of the Uighur Khaganate (744-840 AD) but it is not clear what their motive would be for constructing a fortress for in such a solitary place – as it is far from big settlements and trade routes.
The plot thickens as the way it was built, along with the construction materials use, hint at Chinese architectural tradition.
Scientists were able to use laser mapping to create a 3D image of what the 3.5 hectare plot could have been used for.
Although it is said to be around 1,300 years old, many walls were intact and well preserved with a main structure in the inner courtyard being separated into two parts, covered by a tiled roof walkway supported by 36 wooden columns on stone bases.
The mysterious island, Por-Bajin, was found in the centre of a remote lake high in the mountains of southern Siberia..
