From the Living Among Legends section:
With a continuous history stretching back more than 9,000 years, the Five Kings Mountains and its dwarven culture are truly ancient—and they know it. Statues of legendary heroes, friezes of grand victories, and even millennia-old graffiti remind residents of their storied past, inspiring them to emulate and even surpass their ancestors. Yet that same past can bring stagnation. Cleaving to tradition, dwarven society is often slow to change and slower to question its own shortcomings until some new discovery threatens the status quo.
They don’t yet know it, but your player characters are about to make just such a discovery! The Sky King’s Tomb Adventure Path explores dwarven history and the Darklands, taking your PCs from levels 1 to 10 as they uncover forgotten lore, challenge old legends, and discover a mythical site that could change Five Kings Mountains culture forever.