Xi'an is the capital of Shaanxi province, located in the northwest of the People's Republic of China. One of the oldest cities in China, the city was known as Chang'an before the Ming dynasty. Xi'an is the oldest of the Four Great Ancient Capitals of China, having held the position under several of the most important dynasties in Chinese history, including Zhou, Qin, Han, Sui, and Tang. More than 3,000 years of history including over 1,100 years as the capital city of ancient dynasties, have endowed the city with an amazing historical heritage. Xi'an is the starting point of the Silk Road and home to the Terracotta Army of Emperor Qin Shi Huang. The culture of Xi'an descends from one of the world's earliest civilizations. Xi’an was chosen to host the 2011 World Horticultural Exposition by the Association of International Producers of Horticulture (AIPH) at its 59th congress, held in Brighton. Qinqiang (Voice of Qin) is the oldest and most extensive of the four major types of Chinese opera. Also called "random pluck", Qinqiang is the main type of drama in Shaanxi province. As the earliest ancestor of Beijing Opera, Yu Opera, Chuan Opera and Hebei Opera, Qinqiang has developed its own system of unique vocal music, spoken parts, facial makeup, posture, role, category and acting. It can be traced to Xi Qinqiang in Qin dynasty, and blossomed until Qing dynasty, with direct influences on many branches of Chinese Opera.