Ether is presented as Moroni's abridgment of an even older record than the rest of the Book of Mormon, the twenty four gold plates of a people the text calls the Jaredites. Where the Nephite record traces back to a family leaving Jerusalem around 600 BCE, the Jaredite record traces back further still, to a small group led by a man named Jared and his brother who leave the region of a great tower at the time the text places the confusion of languages, traveling first across a wilderness and then across an ocean in a fleet of small enclosed vessels called barges, sealed against water and lit by stones the text describes as touched and made to shine.
Once settled in a promised land, generally understood within the Book of Mormon's own geography to be the same land the Nephites and Lamanites later occupy, the Jaredites establish a kingdom that cycles repeatedly through righteousness, prosperity, pride and internal war, a pattern the abridged text narrates across many generations and numerous named kings, most of them known only through brief notices of their reigns rather than developed narrative.
Because the Jaredite record predates the Nephite one by more than a thousand years within the Book of Mormon's own chronology, Ether functions as a kind of deep background to the rest of the volume, a much older cautionary cycle of rise and total collapse that the Nephite narrative echoes rather than repeats exactly.