The Amalekites were Nephilim. If you don't know what the Nephilim were, you have some very exciting research ahead.
Start with Genesis 6.
Genesis 36: The Amalekites were a tribe descended from Amalek, the son of Eliphaz and grandson of Esau, (vs 12 and 16). They were related to the Edomites.
'Fraid not, pardner. The Amalekites were descendants of Esau, Israel's twin brother.