According to The Book of Mormon, the hill Amnihu(/æmˈnaɪ.huː/) was located east of the river Sidon and across the river from Zarahemla (Alma 2:15).
A Nephite dissident, Amlici, brought an army to battle the Nephites (Alma 2:17). This battle may have been intended primarily as a diversion, luring the Nephite army away from the capital city. The Amlicites hastily retreated southward, joined with a Lamanite army, and raced to attack the city of Zarahemla.
The hill is mentioned in only two verses: Alma 2:15,17.
References
Hill Amnihu Wikipedia(Text) CC BY-SA