The history of China spans thousands of years, beginning with the emergence of the Xia Dynasty around 2070 BCE. This was followed by notable dynasties such as the Shang and Zhou, which contributed to early Chinese culture, philosophy, and governance. The Qin Dynasty (221-206 BCE) is famous for unifying the country and building the Great Wall. Over the centuries, China experienced periods of prosperity and turmoil, including the Han Dynasty, known for advancements in trade and technology, and the Ming Dynasty, celebrated for its exploration and cultural achievements. The 20th century saw significant changes, leading to the establishment of the People's Republic of China in 1949.