Here is a question about this article: Nanjing, one of the nation's most important cities for over a thousand years, is recognized as one of the Four Great Ancient Capitals of China, and had been the world's largest city aggregately for hundreds of years, enjoyed peace and prosperity and beared wars and disasters. Nanjing served as the capital of Eastern Wu, one of the three major states in the Three Kingdoms period (211-280); the Eastern Jin and each of the Southern Dynasties (Liu Song, Southern Qi, Liang and Chen), which successively ruled southern China from 317-589; the Southern Tang, one of the Ten Kingdoms (937-76); the Ming dynasty when, for the first time, all of China was ruled from the city (1368-1421); and the Republic of China (1927–37, 1945–49) prior to its flight to Taiwan during the Chinese Civil War. The city also served as the seat of the rebel Taiping Heavenly Kingdom (1851–64) and the Japanese puppet regime of Wang Jingwei (1940–45) during the Second Sino-Japanese War, and suffered appalling atrocities in both conflicts, including the Nanjing Massacre. It has been serving as the capital city of Jiangsu province after the China was established, and is still the nominal capital of Republic of China that accommodates many of its important heritage sites, including the Presidential Palace and Sun Yat-sen Mausoleum. Nanjing is famous for human historical landscapes, mountains and waters such as Fuzimiao, Ming Palace, Chaotian Palace, Porcelain Tower, Drum Tower, Stone City, City Wall, Qinhuai River, Xuanwu Lake and Purple Mountain. Key cultural facilities include Nanjing Library, Nanjing Museum and Art Museum.
What is the answer to this question: How long has Nanjing been important?
over a thousand years