The Polynesians are most powerful on the Australian or the South East Asia maps, and to tiny extent on harlan China and My custom 200 by 400 global map. If you had to pick for power you would play as the south east Asia because it covers the ancient homeland in 4,000 BC called Taiwan in the late modern ages 1900 to 2100 AD. more recent tribes with official map are Austronesians (south east Asia), Micronesians (any global but with sea engineers on rocks) or Melananisians (Australia), or Samoan (who are also Polynesian - any global).
This civilization spread across south east Asia into Africa, offshore Australia, and into the deepest part of the pacific ocean. One histroical problem is that in real life all areas colonized by Polynesians were never politically united. In real life only one tribe would politically unite like Maori or Hawaiian. So pick your region and become the sea people race.