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.
Nielam County belongs to Xigaze City, Tibet Autonomous region, between the Himalayas and the Ladaogangri Mountains, connecting with Dingri, Anren, Saga and Jilong counties in the east, north and west, and adjacent to the Kingdom of Nepal in the south. The area is 8684.39 square kilometers. In 2005, the county's GDP reached 178.1 million yuan, with a per capita GDP of 11657 yuan. By the end of 2005, the total population of Nie Lamu County was 15000, including Han, Hui, Tibetan and other ethnic minorities. Nie Lamu County has gold, precious stones, lead, coal and other mineral resources. On September 25, 2018, he won the honorary title of "2018 e-commerce into rural comprehensive demonstration county" of the Ministry of Commerce. In 2017, Nielamu County withdrew from poverty-stricken counties (districts).