Amalek

Amalek was a nation known as an enemy of Israel. They probably descended from Amalek, the son of Eliphaz and his concubine, Timna. As recorded in the Book of Exodus, Israel and Amalek battled at Rephidim on their way away from Egypt. During the reign of Saul and David's military leadership, Israel had a hostile relationship with Amalek consisting of many battles and skirmishes. After David's military campaigns, it appears Amalek was destroyed with only a small surviving remnant.

First Battle with Israel
Amalek first battled Israel in the wilderness of Rephidim. Moses sent Joshua to fight Agag, which might be a title for Amalekite kings. The Lord told Moses that when his hand is raised, Israel would prevail against Amalek but if his hand is down, Amalek will prevail over Israel, so throughout the entire battle Moses has his hands up, with the help of two helpers. Eventually, Israel prevails over Amalek fully.