A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a more resistant layer or layers of harder rock, e.g. shales overlain by sandstones. The resistant layer acts as a caprock that forms the flat summit of a mesa. The caprock can consist of either sedimentary rocks such as sandstone and limestone; dissected lava flows; or a deeply eroded duricrust. Unlike plateau, whose usage does not imply horizontal layers of bedrock, e.g. Tibetan Plateau, the term mesa applies exclusively to the landforms built of flat-lying strata. Instead, flat-topped plateaus are specifically known as tablelands.
Kashgar, one of the five regions of Xinjiang Uygur Autonomous region, is based in Kashgar. Surrounded by mountains on three sides and open on one side, it belongs to the warm temperate continental arid climate zone, with four distinct seasons and long light, with a total area of 162000 square kilometers, under the jurisdiction of 1 city and 11 counties, and a total population of 4.6497 million in 2017. The ancient Kashgar area is known as "Shule" and "Shu Fu", including ancient Shule (present-day Kashgar City, Shufu County, Shule County, Jiashi County), Puli (present-day Tashkurgan), Shacha, Yinai (present-day Yingjisha and Aktao), Wuhe House (present-day Tashkurgan), Xinight (present-day Yecheng) and other places. As the traffic hub of the ancient Silk Road, Kashgar is an international commercial port where Chinese and foreign businessmen gather, and it is also the only national historical and cultural city in Xinjiang.