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I read a book years ago, and now I can't remember the author or title. I do remember that it was like the 3rd or 4th in a series, but I don't remember what the series was called.
In the book, a pilot for an interplanetary empire crash-lands on a planet that has been deemed unsuitable for habitation, and is quarantined. He is rescued by the native people (yes, they are humans), and nursed back to health. When he comes to, he finds out that the people here are a matriarchal society. Royal women can have multiple men, and trade them around for political purposes. They settle disputes, barter, and predict the future with a game using many different dice. The dice are different sizes, shapes, colours, and materials, and the different dice have different point values. They have an air force, but even they have few weapons, and look like giant versions of the dice sets. The planet is extremely technologicaly primitive. The pilot basically teaches the people how to make newer technology, and ends up sparking a war in which people die from violence for the first time in centuries. They kick him out of their society, but he is killed by quarantine sentry turrets as he tries to escape the planet.
Any clue what book this is? I've been trying to remember it because I want to read the entire series. I know that one of the other books in the series is called "The Fourth Tri-" something.