The brother of Jared warned his people that having a king would lead them into captivity (see Ether 6:22–23), and it did. The Jaredite king Kib and later his son Shule were both taken captive by rivals. Notice how quickly the brother of Jared’s prophecy was fulfilled.
A great deal of the Jaredites’ history is covered in chapter 7 of the book of Ether. Moroni recorded only highlights of this history in his abridgement. He emphasized the parallels with his own people and the lessons that would be most valuable for our day.