Oral traditions and scientific evidence indicate Pohnpei to have been settled from areas to the east, south, and west. Archaeological evidence dates the earliest human activity at roughly the beginning of the Christian era. Of particular note is the megalithic site of Nan Madol, located just off the southeastern shore of Pohnpei. Archaeologists estimate that construction began sometime during the thirteenth century A.D. and continued for a period of approximately five centuries. Local histories speak of a line of rulers, the Saudeleurs, who attempted to dominate the island from Nan Madol. Following the fall of the Saudeleurs, there developed a more decentralized system of chieftainship. By the end of the nineteenth century, there were five chiefdoms coexisting with several smaller, autonomous regions that possessed a less stratified system of political organization. Intensified contact with the European-American world in the nineteenth century brought trade, Christianity, new diseases, and social disruption. One of the major patterns of the Pohnpeian past, however, has been a pronounced ability to adapt constructively to forces of change. Resistance to foreign domination has been another strong characteristic of this culture. Pohnpeians resorted to violent resistance against both Spanish (1886-1899) and German (1899-1914) colonial rule. Pohnpeian resistance to later Japanese (1914-1945) and American (1945-1983) colonialism has involved less violent and more subtle cultural forms.