The Dawnchant was a lost language on Roshar kept alive only by the writtings and songs of the Vanrial, an order of artists who sung in the Dawnchant without any knowledge of it's meaning. It was believed by them to be the language spoken by the Heralds.
It was discovered by Navani that Dalinar spoke in the Dawnchant when he entered his trances during the Highstorms and she hoped to be able to translate it by questioning Dalinar as to what he said during his trances.
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