According to The Book of Mormon

Book of Mormon

The Book of Mormon is a sacred text of the Latter Day Saint movement that adherents believe contains writings of ancient prophets who lived on the American continent from approximately 2600 BC to AD 421. It was first published in March 1830 by Joseph Smith, Jr...

, the plains of Agosh were the site of a battle during Jaredite

Jaredite

The Jaredites are a people written of in the Book of Mormon, principally in the Book of Ether. In the Book of Ether, the Jaredites are described as the descendants of Jared and his brother, at the time of the Tower of Babel. According to the Book of Mormon, the people fled across the Ocean via...

times.

We learn of Agosh in only two verses in The Book of Mormon, , 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]).