The First Law World in the order Joe Abercrombie wrote it. The original trilogy establishes the world, its characters, and its moral framework. The standalones expand the geography and revisit familiar characters from new angles - each works independently but rewards readers who know the trilogy. The Age of Madness follows, set a generation later in a changed world. Sharp Ends fits best after the standalones and before Age of Madness, though it can be read at any point after the trilogy. Publication order is the way most readers first experienced the world, and the way Abercrombie built it - each book assumes familiarity with what came before.
The First Law World spans two trilogies, three standalone novels, and a short story collection. The recommended sequence follows publication order with one note: the standalones are best read before The Age of Madness, as several characters from those books return in the sequel trilogy and their histories matter. Start with The First Law trilogy - it establishes the world, the characters, and everything the later books are in conversation with. The standalones can be read in any order after the trilogy. Sharp Ends works best after the standalones rather than as an entry point. The Age of Madness assumes familiarity with the full world and rewards readers who arrive with that context.