The architecture of Mongolia is largely based on traditional dwellings, such as the yurt (, ) and the tent. During the 16th and 17th centuries, lamaseries were built throughout the country as temples which were later enlarged to accommodate a growing number of worshipers. Mongolian architects designed their temples with six and twelve angles and pyramidal roofs approximating the yurt's round shape. Further expansion led to a quadratic shape in the design of the temples, with roofs in the shape of pole marquees. Trellis walls, roof poles and layers of felt were eventually replaced by stone, brick beams and planks. Mongolian artist and art historian N. Chultem identified three styles of traditional Mongolian architecture (Mongolian, Tibetan and Chinese), alone or in combination. Batu-Tsagaan (1654), designed by Zanabazar, was an early quadratic temple. The Dashchoilin Khiid monastery in Ulaanbaatar is an example of yurt-style architecture. The 18th century Lavrin Temple in the Erdene Zuu lamasery was built in the Tibetan tradition. The Choijin Lama Süm temple (1904), now a museum, is an example of a temple built in the Chinese tradition. The quadratic Tsogchin Temple, in Ulaanbaatar's Gandan monastery, combines Mongolian and Chinese traditions. The Maitreya Temple (demolished in 1938) was an example of Tibeto-Mongolian architecture. The Dashchoilin Khiid monastery has begun a project to restore this temple and the sculpture of Maitreya. Indian influences can also be seen in Mongolian architecture, especially in the design of Buddhist stupas. Ancient period The Xiongnu confederation ruled present-day Mongolia from the third century BCE through the first century CE, living in portable, round tents on carts and round yurts. The Xiongnu aristocracy lived in small palaces, and their villages were protected by huge walls. S. I. Rudenko also mentions capital construction built of logs. Archaeological excavations indicate that the Xiongnu had towns; their chief city was Luut Hot (Dragon City). Powerful states developed by Turkic tribes from the sixth through ninth centuries dominated the region. and there were several Turkic cities and towns in the Orkhon, Tuul and Selenga River valleys. The main city of the Turkic Khaganate was Balyklyk. The Uyghur Khaganate which succeeded the Turks centred on the city of Kara Balgasun, founded during the early eighth century. A portion of the -high fortress wall with a watchtower has been preserved. A large craft trading district existed in the city, whose architecture was influenced by Sogdian and Chinese traditions. Archaeological excavations