The Amalekites were a biblical people and enemy of the Israelites. They were reportedly wiped out almost entirely as the result of Israelite victories against them in wars beginning shortly after the Exodus and continuing into the period of the early Israelite monarchy. Amalekite settlements are reported in the biblical record as late as the reign of King Hezekiah in the eighth century B.C.E., and the Book of Esther portrays its later villain, Haman, as a descendant of an Amalekite prince.

The Amalekites are unknown historically and archaeologically outside of the Bible except for traditions which themselves apparently rely on biblical accounts.
In the Bible, the Amalekites are said to have descended from a common ancestor named Amalek, a grandson of Esau. In this sense they may be considered as one of the Edomite tribes.
Jewish tradition sees the Amalekites as an implacable enemy of both God and Israel.

Biblical account

The first reference to the Amalekites is found in Genesis 14, which describes a military campaign of Kedorlaomer, king of Elam, and his allies which took place in Abraham's day before the birth of Isaac.
Kedorlaomer conquered territories of the Amalekites, the Horites of Seir, Amorites, and others.
On the other hand, Genesis 36:12 describes the birth of Amalek himself as Esau's grandson, born four generations after the events of Kedorlaomer's time. This account makes the Amalekites one of the Edomite tribes, descended from Esau's firstborn son, Eliphaz. Amalek's mother was named Timna, a Horite princess descended from Seir, for whom Edom's Mount Seir was named.

extracted from https://www.newworldencyclopedia.org/entry/Amalekite