The ancestors of the Micronesians settled over four thousand years ago. A decentralized chieftain-based system eventually evolved into a more centralized economic and religious culture centered on Yap.
Nan Madol, consisting of a series of small artificial islands linked by a network of canals, is often called the Venice of the Pacific. It is located on the eastern periphery of the island of Pohnpei and used to be the ceremonial and political seat of the Saudeleur dynasty that united Pohnpei's estimated 25,000 people from about AD 500 until 1500, when the centralized system collapsed.
European explorers—first the Portuguese in search of the Spice Islands (Indonesia) and then the Spanish—reached the Carolines in the sixteenth century. The Spanish incorporated the archipelago to the Spanish East Indies and in the 19th century established a number of outposts and missions. In 1887, they founded the town of Santiago de la Ascension in what today is Kolonia on the island of Pohnpei.