American Tract Society Bible Dictionary 
Descendants of Moab the son of Lot, Genesis 19:30-38 . The land of Moab lay east and southeast of the Dead Sea, and chiefly south of the river Arnon. At one period, however, it extended north as far as the Jabbok, and for a long time the region beyond the Jordan opposite Jericho retained the name of "the plains of Moab," Numbers 22:1 Deuteronomy 1:5 29:1 Joshua 13:32 . The Moabites had dispossessed a race of giants called Emin, Deuteronomy 2:11 , and had themselves been expelled by the Amorites from the territory north of the Arnon, Numbers 21:13,26 Judges 11:13-18 , which was again conquered by Moses, and assigned to the tribe of Reuben. On the approach of Israel from Egypt, the Moabites acted with great inhumanity, Numbers 22:1-24:25 Deuteronomy 2:8-9; and though God spared them from conquest, he excluded them and their seed even to the tenth generation form the peculiar privileges of his people, Deuteronomy 23:3-6 . They were gross idolaters, worshipping Chemosh and Baalpeor with obscene rites, Numbers 25:1-18 2 Kings 3:27 . See Moloch
At times, as in the days of Ruth, there was peace between them and Israel; but a state of hostility was far more common, as in the time of Eglon, Judges 3:12-30; of Saul, 1 Samuel 14:47; of David, 2 Samuel 8:2,12; of Joram and Jeroboam, 2 Kings 3:13,20 14:25 . They aided Nebuchadnezzar against the Jews, 2 Kings 24:2 Ezekiel 25:6-11; and after these began to be carried captive, appear to have regained their old possessions north of the Arnon, Isaiah 15:1-16:14 . The Jewish prophets recorded many threatenings against these hereditary enemies of God and his people, Numbers 24:17 Psalm 60:12 83:6 Jeremiah 25:9-21 48:1-47 Amos 2:1-3; and all travelers concur in attesting the fulfillment of these predictions. Desolation and gloom, brood over the mountains of Moab, and its fruitful valleys are for the most part untilled. It is under Turkish government, but is inhabited chiefly by migratory Arabs, Zephaniah 2:8-9 . Few travelers have ventured to traverse it in modern times. They describe it as abounding in ruins, such as shattered tombs, cisterns walls, temples, etc., proving that it was once densely populated. See "Keith On Prophecy"
Kitto's Popular Cyclopedia of Biblial Literature 
Mo´abites, a tribe descended from Moab the son of Lot, and consequently related to the Hebrews . Previous to the exodus of the latter from Egypt, the former, after expelling the original inhabitants, called Emims , had possessed themselves of the region on the east of the Dead Sea and the Jordan, as far north as the River Jabbok. But the northern, and indeed the finest and best, portion of the territory, viz. that extending from the Jabbok to the Arnon, had passed into the hands of the Amorites, who founded there one of their kingdoms, with Heshbon for its capital , Og had established another at Bashan. Hence at the time of the exodus the Valley and River Arnon constituted the northern boundary of Moab . As the Hebrews advanced in order to take possession of Canaan, they did not enter the proper territory of the Moabites , but conquered the kingdom of the Amorites (a Canaanitish tribe), which had formerly belonged to Moab; whence the western part, lying along the Jordan, frequently occurs under the name of 'plains of Moab' . The Moabites, fearing the numbers that were marching around them, showed them at least no kindness , and their king (Balak) hired Balaam to utter prophetic curses, which, however, were converted into blessings in his mouth (Numbers 22 sq.). The Gadites now took possession of the northern portion of this territory, which the Amorites had wrested from the Moabites, and established themselves there; while the Reubenites settled in the southern part (; comp. Joshua 13, which, however, differs somewhat in the designation of particular towns).
We see the first hostilities breaking out in the beginning of the period of the Judges, when the Hebrews had been for a long time tributary to the Moabites, but threw off their yoke under Ehud . Towards the end of this period, however, peace and friendship were restored, mutual honors were reciprocated (as the history of Ruth shows), and Moab appears often to have afforded a place of refuge to outcasts and emigrant Hebrews (; comp.;; ). After Saul had waged successful war against them , David made them tributary (;; ). The right to levy this tribute seems to have been transferred to Israel after the division of the kingdom; for upon the death of Ahab (about B.C. 896), they refused to pay the customary tribute of 100,000 lambs and as many rams (;; comp. ). Jehoram (B.C. 896), in alliance with Judah and Edom, sought indeed to bring them back to their subjection. The invading army, after having been preserved from perishing by thirst through the intervention of Elisha, defeated the Moabites and ravaged the country; but, through the strange conduct of the king, in offering up in sacrifice his son [MESHA], were induced to retire without completing the object of the expedition. The Moabites deeply resented the part which the king of Judah took in this invasion, and formed a powerful confederacy with the Ammonites, Edomites, and others, who marched in great force into Judea, and formed their camp at Engedi, where they fell out among themselves and destroyed each other, through the special interposition of Providence in favor of Jehoshaphat and his people (, sq.; comp. ) [[[Elisha; Jehoram; Jehoshaphat]]] Under Jehoash (B.C. 849) we see them undertake incursions into the kingdom of Israel, and carry on offensive war against it .
Though the subsequent history of Israel often mentions the Moabites, yet it is silent respecting a circumstance which, in relation to one passage, is of the greatest importance, namely, the re-conquest of the territory between the Arnon and the Jabbok, which was wrested from the Moabites by the Amorites, and afterwards of the territory possessed by the tribes of Reuben and Gad. This territory in general we see, according to Isaiah 16, in the possession of the Moabites again. Even Selah, the ancient capital of the Edomites, seems likewise, from , to have belonged to them, at least for a time. The most natural supposition is, that, after the carrying away of those tribes into captivity, the Moabites occupied their territory; as it is expressly stated that the Amorites intruded themselves into the territory of the captive Gadites, as the Edomites did in respect to the Jews at a later period.
Still later, under Nebuchadnezzar, we see the Moabites acting as the auxiliaries of the Chaldeans , and beholding with malicious satisfaction the destruction of a kindred people yet, according to an account in Josephus (Antiq. x. 9. 7), Nebuchadnezzar, when on his way to Egypt, made war upon them, and subdued them, together with the Ammonites, five years after the destruction of Jerusalem.
That continual wars and contentions must have created a feeling of national hostility between the Hebrews and the Moabites, may be readily conceived. This feeling manifested itself on the part of the Hebrews, sometimes in bitter proverbs, sometimes in the denunciations of the prophets; on the part of the Moabites in proud boastings and expressions of contempt .
Among the prophecies, however, that of Balaam (Numbers 22-24) is above all remarkable, in which this ancient prophet (who withal was not an Israelite), hired by Moab to curse, is impelled by the Divine Spirit to bless Israel, and to announce the future destruction of Moab by a mighty hero in Israel . The destruction of the Moabites for their scorn and contempt of Israel is predicted by Jeremiah, Ezekiel, Amos, and Zephaniah.
After the exile an intimate connection between the two nations had found place by means of intermarriages (, sq.; ), which, however, were dissolved by the theocratic zeal of Ezra. The last (chronologically) notice of the Moabites which occurs in Scripture is in , which contains an obscure intimation of the escape of the Moabites from the overthrow with which neighboring countries would be visited (Antiq. xiii. 13. 5). Thenceforth their name is lost under that of the Arabians, as was also the case with Ammon and Edom. Until of late the accounts of the territory of Moab are uncommonly meager, but within these few years it has been explored by various travelers, who have shed a new light on the topography of this region.
From their researches we learn that in the land of Moab, which lay to the east and southeast of Judea, and which bordered on the east, north-east, and partly on the south of the Dead Sea, the soil is rather more diversified than that of Ammon; and, where the desert and plains of salt have not encroached upon its borders, of equal fertility. There are manifest and abundant signs of its ancient importance. The whole of the plains are covered with the sites of towns on every eminence or spot convenient for the construction of one; and as the land is capable of rich cultivation, there can be no doubt that the country, now so deserted, once presented a continued picture of plenty and fertility. The form of fields is still visible, and there are remains of Roman highways which are in some places completely paved, and on which there are milestones of the times of Trajan, Marcus Aurelius, and Severus, with the numbers of the miles legible upon them. Wherever any spot is cultivated the corn is luxuriant; and the frequency and almost, in many instances, the close vicinity of the sites of ancient towns, prove that the population of the country was formerly proportioned to its fertility. It was in its state of highest prosperity that the prophets foretold that the cities of Moab should become desolate, without any to dwell in them; and accordingly we find, that although the sites, ruins, and names of many ancient cities of Moab can be traced, not one of them exists at the present day as tenanted by man. The argument for the inspiration of the sacred records deducible from this, among other facts of the same kind, is produced with considerable force by Dr. Keith in his work on Prophecy.