The remains of three major Neolithic cultures in ancient China, Beixin culture, Dawenkou culture, and Longshan culture have been found in Zibo. Ancient Linzi, located in present-day Zibo, was the capital of the ancient State of Qi, a powerful state during the Spring and Autumn and the Warring States periods, over 2,000 years ago. In 7th century BC, Duke Huan of Qi, ruler of Qi, appointed Guan Zhong, thinker and economist, as his prime minister, and adopted Guan's thoughts and policies to administer his country, develop the economy and develop relations with other states. The measures greatly strengthened the country, making its capital one of the most prosperous in ancient China. Zibo is rich in cultural and historical sites, and is referred to as the "Underground Museum". In Linzi, the ruins of the ancient Qi city, as well as other famous cultural relics and historic sites, have been discovered and unearthed. The ancient city of Qi was one of the first places in China that was assigned to be a "cultural relics site" and protected.