It claims to be based on history. I think the main points are probably historically accurate, but lots of details are fiction to fill in the gaps so they can tell a story we'd want to watch.
Wow the Polynesians are phyically impressive. Athletic giants in the 1700s and still big today. Maybe a bit less athletic in modern times due to less exercise in modern life style and liking SPAM way too much. The Pacific Islanders are the only people I know of who think SPAM is a delicacy. I've had some of their cooking with SPAM in it. They do make it delicious.