40 kilometers (25 miles) southeast of Turpan, 6 kilometers (3.7 miles) from the ancient city of Gaochang, this Tang-dynasty burial ground known as the "Underground Museum" attracts stream of archaeologists both at home and abroad Astana means "capital" in Uigur and Karakhoja is the name of a legendary hero of the ancient Uigur Kingdom who expelled the evils by killing a vicious dragon. Two villages nearby name after these two.

The tombs range 2 kilometers (1.24 miles) from north to south and 5 kilometers (3.1 miles) from east to west. The imperial dead of Gaochang and noble officials were buried here. However, curiously, the tomb of King Gaochang has been found nowhere in the tombs.

A 10-meter (16-feet) steep, narrow passage leads down into a small dark chamber where the corpses were lay down. The dry climate preserved the bodies and artifacts perfectly. Dried-up corpse, the one more unusual than the mummies found in the pyramids in Egypt, remain complete and intact. A fine collection of relics from Astana including painted stucco figurines which revealed such aspects of daily life as traditional costumes, customs and riding accoutrements are exhibited in the Xinjiang Regional Museum in Urumqi. Remains of grains, breads, pastries and dumplings placed in the graves gave insight into their diet. Furthermore, on a bail of horse fodder are written the words "Judge Cen" and "Minister Feng". Judge Cen is the famous frontier poet Cen Shen of the Tang Dynasty and Minister Feng, the governor of Beiting Prefecture of the Tang Dynasty. Most buried here were people of the Han, but also some minority nationalities, such as the Cheshi, Hun, Di, Xianbei, Gaoche, and Zhaowujiuxing.

Now three tombs have been opened to visitors. In the tomb of the Tang Dynasty, General Zhang Xiong of the Qushi Gaochang Kingdom was buried here with his wife (now encased in the Turpan Regional Msueum). There are four murals depicting Jade Man, Gold Man, Stone Man and Wooden Man - all symbols of Confucian virtues.

The city was brought under the protection of the state in 1961.