Chengdu (UK: , US: , Standard Mandarin: [ʈʂʰə̌ŋ.tú] (listen)), formerly romanized as Chengtu, is a sub-provincial city which serves as the capital of Sichuan province, People's Republic of China. It is one of the three most populous cities in Western China, the other two being Chongqing and Xi'an. As of 2014, the administrative area housed 14,427,500 inhabitants, with an urban population of 10,152,632. At the time of the 2010 census, Chengdu was the 5th-most populous agglomeration in China, with 10,484,996 inhabitants in the built-up area including Xinjin County and Deyang's Guanghan City. Chengdu is also considered a World City with a "Beta +" classification according to the Globalization and World Cities Research Network.The surrounding Chengdu Plain is also known as the "Country of Heaven" (Chinese: 天府之国; pinyin: Tiānfǔ zhi Guó) and the "Land of Abundance". Its prehistoric settlers included the Sanxingdui culture. Founded by the state of Shu prior to its incorporation into China, Chengdu is unique as a major Chinese settlement that has maintained its name (nearly) unchanged throughout the imperial, republican, and communist eras. It was the capital of Liu Bei's Shu during the Three Kingdoms Era, as well as several other local kingdoms during the Middle Ages. It is now one of the most important economic, financial, commercial, cultural, transportation, and communication centers in Western China. Chengdu Shuangliu International Airport, a hub of Air China and Sichuan Airlines is one of the 30 busiest airports in the world, and Chengdu railway station is one of the six biggest in China. Chengdu also hosts many international companies and more than 12 consulates. More than 260 Fortune 500 companies have established branches in Chengdu.