We learn of Agosh in only two verses in The Book of Mormon, [[s:Book of Mormon/Ether#14 15|Ether14 15-16]], when Coriantumr and all the people who followed him, retreated to these plains before facing their enemies, led by Lib. Coriantumr killed Lib in battle, but Lib's brother took command of the army and Coriantumr again fled. References are from The Book of Mormon: Another Testament of Jesus Christ, translated by Joseph Smith, Jr. (Salt Lake City, Utah: The Church of Jesus Christ of Latter-day Saints, 1981 [first edition, 1830]).