Claim: BYD Auto is based in China.

Xi'an -LRB- -LSB- - cmnAUDZh-Xi ` an.oggxi1.an1 -RSB- -RRB- , formerly romanized as Sian , and also known as Chang ` an '' ' -LRB- -LSB- - cmnAUDZh-Changan . oggchang2.an1 -RSB- -RRB- before the Ming dynasty , is the capital of Shaanxi Province , People 's Republic of China . It is a sub-provincial city located in the center of the Guanzhong Plain in Northwest China . One of the oldest cities in China , Xi'an is the oldest of the Four Great Ancient Capitals , having held the position under several of the most important dynasties in Chinese history , including Western Zhou , Qin , Western Han , Sui , and Tang . Xi'an is the starting point of the Silk Road and home to the Terracotta Army of Emperor Qin Shi Huang .   Since the 1990s , as part of the economic revival of inland China especially for the central and northwest regions , the city of Xi'an has re-emerged as an important cultural , industrial and educational centre of the central-northwest region , with facilities for research and development , national security and China 's space exploration program . Xi'an currently holds sub-provincial status , administering 9 districts and 4 counties . Xi'an has a population of 8,705,600 and the Xi'an - Xianyang metropolitan area has a population of 13,569,700 . It is the most populous city in Northwest China , as well as one of the three most populous cities in Western China . According to a July 2012 report by the Economist Intelligence Unit , it was recently named as one of the 13 emerging megacities , or megalopolises , in China . The report pinpoints and highlights the demographic and income trends that are shaping these cities ' development .