The Mangaians have an unusual legend of their early history. Most Polynesian islands have some sort of legend about a great ancestor arriving on a fantastic canoe, but not the Mangaians. Nobody sailed from anywhere to become Mangaia's first settler. Rangi, Mokoiro and Akatauira, the three sons of the god Rongo, father of Mangaia, simply lifted the island up from the deep, becoming its first settlers and the ancestors of the Nga Ariki tribe.
The traditional name of the island was A'u A'u (literally 'terraced' - named for the 'steps' of the makatea), short for A'u A'u Nui o Rongo ki te Ao Marama (Big Terraced Land of Rongo in the World of Daylight).
The island's current name is comparatively new; it is short for a name bestowed by Tamaeu, an Aitutakian who arrived on Mangaia in 1775. Mangaia means 'Peace' or 'Temporal Power' - the name relates to 42 battles between the island's various groups and the peace that was finally established when one leader eventually achieved mangaia (power) over the whole island.
Two years later, James Cook claimed the European discovery of Mangaia during his second Pacific voyage. He arrived on 29 March 1777, but the Mangaians gave him a frosty welcome, so Cook sailed north to find a friendlier greeting at 'Atiu.
Uniquely in the Cook Islands, cannibalism had already been outlawed by the time the missionaries turned up in 1823. The great Mangaian chief Mautara had banned the practice almost a century before: since most Mangaians were related in some way, either by blood or marriage, Mautara decided that family harmony was probably not best served by the custom of serving up your siblings for dinner.
Nevertheless, the missionaries were not given the warmest of receptions when they first arrived. The pioneering missionary John Williams stumbled across the island in 1823 while he was searching for Rarotonga. He attempted to set Polynesian missionaries ashore, but the Mangaians attacked them, so Williams promptly dropped the idea and sailed off again. A couple of missionaries from Tahaa (in present-day French Polynesia) landed in 1824, and although they were fairly inept, their successor, the Rarotongan preacher Maretu, eventually had more success. Maretu's book Cannibals & Converts describes Mangaia's conversion to Christianity.
Like many of the outer islands, Mangaia is struggling with an ongoing population decline. Since the mid-1970s the population of the island, stable for some time at around 2000, has fallen to almost a third of that, and so far the trend shows no sign of reversing.