Ingenieur Vol 80 ingenieur 2019 octoberfinal | Page 76

INGENIEUR Ancient Jiahoe City, China By Chin Siew Yin T he city of Turpan is a prefecture-level city located in the east of Xinjiang province, People's Republic of China. Just 10km west of Turpan city, lies the abandoned city of Jiaohe which was once a thriving ancient city. Jiaohe means “where two rivers meet”. What remains now are the ruins of buildings, roads and basic facilities that are now maintained under the heritage body administration. I took a trip there to understand the history and the construction techniques of that bygone era. After a 30-minute ride from Turpan city, I was guided to an isolated modern museum shaped like an old fortress. At the entrance hall, there was a big sign proclaiming “Jiaohe ancient city – the world’s only city built with natural earth”. Another signboard displayed the phrase “A place where two rivers meet; the birth place of wisdom”. There were also photos and artifacts narrating the history of the creation of this city and its destruction by attackers, and its eventual abandonment until this day. The site of the ruins of Jiaohe’s ancient city is about 1km away from the isolated museum and we were transported to it in a 30-seater electric buggy. From 108 BC to 450 AD, Jiaohe was the capital of the Anterior Jushi Kingdom. It was an important site along the Silk Road trade route leading to the west, and was adjacent to the Korla and Karasahr kingdoms to the west. From 450 AD until 640 AD it became Jiao prefecture in the Tang Dynasty. In 640 AD, it was made the seat of the new Jiaohe County. From 640 AD until 658 AD, it was also the seat of the Protector General of the Western Regions, the highest level military post of a Chinese military commander posted in the west. Since the beginning of the ninth century it had become Jiaohe prefecture of the Uyghur Khaganate, until their kingdom was conquered by the Kyrgyz soon after in the year 840. Jiaohe City Plan The city was built on a large islet in the middle of two rivers, which formed natural defenses. It 6 74 VOL 2019 VOL 80 55 OCTOBER-DECEMBER JUNE 2013 is 1,650m in length and 300m wide at its widest point. Steep cliffs more than 30m high on all sides of the river acted as natural walls. This explains why the city was built without walls. The layout of the city consists of eastern and western residential districts, while the northern district was reserved for Buddhist sites of temples and stupas. Along with these, there are notable graveyards and the ruins of a large Government office in the southern part of the eastern district. At its peak, it had a population of 7,000, according to Tang dynasty records. It was finally abandoned after its destruction during an invasion by the Mongols, led by Genghis Khan, in the 13 th century. Building Structure Besides the absence of walls, the building style has another significant feature, i.e. most buildings, including wide streets, were cut out of the primary earth. Cave dwellings were also directly cut from the primary earth. Most of the single-storey houses were composed of four walls left after cutting through the primary earth and supported by wood. Some of them were carved into the cliff or dug into the earth, while others were built by piled up earth. There is only one large residential building made from brick blocks. All of the residential buildings had two floors: one aboveground and one underground. Although abandoned a long time ago, they are well preserved. The lack of rain and the arid climate in the region throughout the last few centuries are likely reasons why Jiaohe city’s structures avoided significant decay. Adobe materials, which are a mixture of earth and straw made into bricks and dried in the sun for construction, commonly used in ancient buildings, were not that visible in the Jiaohe ruins. During the Uyghur period, adobe materials were widely used to build vaulted roofs, which is evidenced by the vaulting grooves left on the walls of many rooms.