At the end of the first millennium B.C. construction of strong fortresses began in the West Pamirs due to the threat of military attacks by neighbours. The first was the Yamchun fortress built in the 3rd century B.C. On the right bank of the Panj River in the foothills of the Wakhan range.
It stands on a cliff continually washed by tributaries of the Panj – the Yamchun and Vikhut Rivers – the steep banks of which are inaccessible the whole year round. The slope was used in planning the fortress. It was built in a triangle shape with its base pointing into the valley. Consisted of three parts citadel, bastion and the barracks surrounded with walls. Strengthened by rectangular towers and two squares, each of which was also surrounded by highwalls. Fortified with 36 rectangular and oval towers with embrasures (portholes). In case of attack a huge number of people could hide inside the fortress. The walls have no foundations and they are made of machine-tiled stones on a solid clay base.
The total height of the walls is about 3m and the width about 1.5m. There are 2 sets of fortress walls, one inside the other. The outer wall, up to 2m thick, is either made entirely of stones, or of stones in the lower part and unbaked bricks in the upper part. The inner wall is similar to outside one, but is only 50–60cm thick. It also has crack portholes directed inside the fortress. The distance between the outer and inner walls is about 2m. All the walls are connected by chain of towers equipped with thin portholes about 1m high. Approximately 30cm wide, arranged like a chessboard in a staggered order with a few layers covered with slightly-angled tiles to allow marksmen in the fortress to defend the Panj valley from several sides.
Towers are about 3.5–4m in diameter. The walls are 1-1.5m thick, and the distance between the portholes is 2-5m. Towers were constructed with stones with occasional clay grout and in some places covered by clay plaster. The upper side of some of the towers is made of baked bricks. Most of the towers are equipped with portholes pointing outwards as well as inwards. And even inside the inter-wall corridors and compartments, which considerably increases the defensive capability of the towers and, hence, the fortress. Stones for constructing the Yamchun Fortress must have been brought from various remote areas. Since there were metamorphic rock, granite and slate rocks, biotite pieces and other forms of mica.
The size of the fortress is striking. This powerful structure was of the greatest importance for the area. Defending against approaches from every side. It was a strategically placed and well-built complex that allowed the supervision of people and shipment flows from the Pamirs to ancient Bactria (Tahoriston), India and Iran and back. However, some aspects of the fortress are puzzling. Panj valley with a 2.5-3km wide river floodplain next to the fortress, is absolutely flat. And Panj flows down not against the northern but the southern slope of the mountain. How could ancient people shoot into the valley with arrows. Which were most likely the main weaponry at that time – during enemy attacks? An arrow’s range is not very long. Perhaps the Panj River at one time ran closer to the right-bank slope, even propping it up. This question remains unanswered.
There is a hot radon spring 1-2km from the fortress. Medicinal water wells up from under the mountain at a temperature of 40-42ºC. The water is useful for treatment of gastro-intestinal, liver, gall-bladder, joint. Bone, musculoskeletal, urological and gynecological disorders. There is a sanitarium half a kilometer from the spring where one can stay overnight.