Almost every island culture has a unique origin or origins outside the Cook Islands. The only exceptions are Manihiki and Rakahanga, which trace a common origin from Rarotonga, and it is possible that the first of many migrations into Mangaia was also from Rarotonga. Rarotonga itself traces its earliest settlers to the Marquesas early in the Christian era, but these peoples were dominated by a migration perhaps 800 years ago from Raiatea in the Society Islands. A migration from Manu'a in Samoa, led by the defeated chief Tui Manu'a, had a significant but not dominant influence on Rarotongan history, though not on its culture. Later migrants from rious islands of Polynesia were absorbed but seem not to have had any cultural impact. The other islands trace their origins mainly to the Society Islands, excepting Pukapuka's diverse origins from the west and occasional later incursions, such as that of Tongans to Mangaia long after settlement by Eastern Polynesians. It is also possible that Tongareva, the northern-most atoll, was settled very early by Western Polynesians, with Eastern Polynesian influence following later. Settlement by Europeans and others was never extensive, but it was very Influential in bringing radical change to the religion, technology, economy, political system, and some values.