Video from greenlantern129
"Who were the Amalekites mentioned in the Bible? Why is it important that we should know about them?" from video introduction.
"Amalek and Israel
According to the Bible, Amalek was the first enemy that Israel encountered after the crossing of the Sea of Reeds. Inasmuch as contemporary archaeology has convinced most biblicists that the biblical traditions of enslavement in Egypt, wilderness wandering, and conquest of the land are unhistorical, traditions about Amalek and Israel in the pre-settlement period probably reflect later realities. In effect, by setting encounters with Amalek in the days of Moses and Joshua, the writers of the Bible were saying that hostilities existed from time immemorial. Among these traditions we find that Amalekites attacked the Israelites in a pitched battle at Rephidim, which, to judge by the Bible (Ex. 17:6, 7, 8–16; 18:5), is in the neighborhood of Horeb; if the locality Massah and Meribah (17:7) is to be found in the region of Kadesh-Barnea or is identical with it (Num. 20:1–14, 24; Ezek. 47:19), then this battle was waged in the northern part of the Sinai Peninsula. The Book of Exodus relates that Joshua fought against Amalek under the inspiration of Moses, who was supported by Aaron and Hur, and that he mowed them down with the sword. Amalek was not destroyed, however, and at the end of this war Moses was ordered to write in a document, as a reminder, that the Lord would one day blot out the memory of Amalek from under the heaven. In commemoration of the victory, Moses built an altar which he called "YHWH-Nissi," and proclaimed that "The Eternal will be at war against Amalek throughout the ages." This implies that Israel is commanded to wage a holy war of extermination against Amalek (Deut. 25:12–19), for in the early days "the wars of Israel" and the "wars of the Lord" were synonymous expressions (cf., e.g., Judg. 5:23). In the biblical traditions, Israel, after sinning through cowardice and lack of faith as a result of the discouraging report of the spies, turned around and "defiantly marched to the crest of the hill country" (Num. 14:44–45) against the divine command and was punished by sustaining a shattering blow at the hands of the Amalekites and Canaanites who inhabited the hill country, the former no doubt being confined to its southernmost end (Num. 14:45). In this particular case, therefore, YHWH, who according to Exodus 17:16 had sworn eternal enmity to Amalek, permitted Amalek to defeat Israel, but, since He had specifically warned Israel against this particular undertaking, there is no real contradiction between Exodus 17:16 and Numbers 14:45. It is possible that this tradition is based on abortive attempts by Israel to expand its holdings in the South during the premonarchic period (see Num. 13:29; 21:1–3, 4–34; Deut 1:44). More closely historical than the Pentateuch's accounts of Amalek are the traditions set in the period of the Judges and the monarchy. During the period of the Judges, the Amalekites participated with other nations in attacks on the Israelite tribes. Together with the Ammonites, they joined Moab against Israel and were among those who captured "the city of palms" – apparently Jericho or the pasture lands of Jericho (Judg. 3:12–13). It seems probable that the wanderings of the Amalekites, or of a particular part of them, extended as far as Transjordan in the neighborhood of Moab or Ammon. (Some scholars (Edeleman in Bibliography) have argued that there was a northern Amalekite enclave adjoining Ephraimite territory.) The Amalekites and the people of the East joined the Midianite raids on the Israelites in the time of Gideon, and, like true desert tribes, undoubtedly participated in the destruction of the crops, as related in the Book of Judges (6:1–7). The Amalekites took part in the battles in the valley of Jezreel (6:33; 7:12) and perhaps also in the Jordan Valley, but there is no evidence that Gideon also fought with the Amalekites in his pursuit of the Midianites in Transjordan. In no case did the Amalekites as a whole suffer decisive defeat at this time and their center in the Negev was not harmed..." from the article: Ancient Jewish History: The Amalekites