The Medes, (Greek Μῆδοι, from an Old Persian 𒈠𒁕𐎭𐎠𐎡 Mādai; Middle Persian Māh, Assyrian 𒈣𒁕𐎹 Mādāyu, New Persian مادها Mād) were an ancient Iranian people who lived in the northwestern portions of present-day Iran. This area is known as Media (also Medea; Greek Μηδία, Old Persian Māda; the English adjective is Median, antiquated also Medean). They entered this region with the first wave of Iranian tribes, in the late second millennium BC (the Bronze Age collapse). By the 6th century BC, after having together with the Babylonians defeated the Neo-Assyrian Empire, the Medes were able to establish their authority, lasting for about sixty years, from the sack of Nineveh in 612 BC until 549 BC when Cyrus the Great established the Achaemenid Empire by defeating Astyages, king of Media.
According to Herodotus, "the Medes were called anciently by all people Aryans; but when Media, the Colchian, came to them from Athens, they changed their name. Such is the account which they themselves give."  Medea is the daughter of the Colchian King Aeëtes in the Greek myth, Jason and the Argonauts. There is not a clear Indo-European etymology for the name of Medes, Mâda. 
Herodotus, i. 101, lists the names of six Median tribes: "Thus Deioces collected the Medes into a nation, and ruled over them alone. Now these are the tribes of which they consist: the Busae, the Paretaceni, the Struchates, the Arizanti, the Budii, and the Magi" (7.62), names of three of these have Iranian etymologies. 
Gudea ruler of Lagash in Mesopotamia (2143-2124 BCE) mentioned "Mada" as a land that grains grow in it. Šulgi ruler of third Ur dynasty (2095-2048 BCE) built "bád mada ki" that means wall of Media. "ki" is a descriptive symbol that comes after geographical places. A lot of translators translate "mada" generally into land. "mada" uses as a suffix before names of lands that are located in west of Iranian plateau like "Martu", "Subartu", "Anšan", "Kimaš", "Gutium" and etc. "Šu-Sin" ruler of third Ur dynasty (2038-2030 BCE), reported his military expedition to lands and cities of Zagros, and pillage of gold from "Mada". Translation of "Mada" as a desert isn't correct because all of lands uses after "Mada" are located in mountains and plateau.
The prehistoric origin of the Medes lies in the common Indo-Iranian homeland in the Eurasian steppes. The early Iranian expansion takes them towards the Persian Plateau and the Zagros mountains during the later second millennium BC as part of the population movements associated with the Bronze Age collapse.
According to Karen Radner, judging by Assyrian sources it is not clear whether Medes were considered to form a distinct ethnic or linguistic identity.
Josephus relates the Medes (OT Heb. Madai) to the biblical character, Madai, son of Japheth. "Now as to Javan and Madai, the sons of Japhet; from Madai came the Madeans, who are called Medes, by the Greeks" Antiquities of the Jews, I:6.
According to the Book of Jubilees (10:35-36), Madai had married a daughter of Shem, and preferred to live among Shem's descendants, rather than dwell in Japheth's allotted inheritance beyond the Black Sea; so he begged his brothers-in-law, Elam, Asshur and Arphaxad, until he finally received from them the land that was named after him, Media. The Kurds still maintain traditions of descent from Madai.
We can see how the Persian element gradually became dominant; princes with Persian names occasionally occur as rulers of other tribes. But the Gelae, Tapuri, Cadusii, Amardi, Utii and other tribes in northern Media and on the shores of the Caspian may not have been Persian stock. Polybius (V. 44, 9), Strabo (xi. 507, 508, 514), and Pliny (vi. 46), considered the Anariaci to be among these tribes; but this name, meaning the "non-Arians", is probably a comprehensive designation for a number of smaller indigenous tribes.
The story that Ctesias gave (a king named Pharnus, said to have been crucified by the Assyrian Ninus in c. 2175 BC, followed by a list of nine later kings beginning with Arbaces, said to have destroyed Nineveh in 880s BC; preserved in Diodorus ii. 32 sqq. and copied by many later authors) has no historical value whatsoever; though some of his names may be derived from local traditions.
The Medes, people of the Mada (the Greek form Μῆδοι is Ionic for Μᾶδοι), appear in Assyrian record first in 836 BC. Earliest records show that Assyrian conqueror Shalmaneser III received tribute from the "Amadai" in connection with wars against the tribes of the Zagros. His successors undertook many expeditions against the Medes (Madai).
In 715 BC and 713 BC, Sargon II of Assyria subjected them up to "the far mountain Bikni" (Damavand or Alvand) and the borders of the desert. If the account of Herodotus is to be trusted, the Median dynasty descends from Deioces (Daiukku) a prince from Diauehi and a Median chieftain in the Zagros, who, along with his kinsmen, was transported by Sargon to Hamath (Haniah) in Syria in 715 BC. This Daiukku seems to have originally been a governor of Mannae, subject to Sargon prior to his exile.
In spite of repeated rebellions by the early chieftains against Assyrian rule, the Medes paid tribute to Assyria under Sargon's successors, Sennacherib, Esarhaddon and Ashur-bani-pal whenever these kings marched against them. Assyrian forts located in Median territory at the time of Esarhaddon's campaign (ca. 676) included Bit-Parnakki, Bit-kari and Harhar (Kar-Sharrukin).
The Median homeland, as can be understood through Assyrian sources, was on the northwest bounded to the land of Mannaeans, on the west to Parsua, on the southwest to Ellipi and on the south to Simashki region of the Elamites. The eastern border of the Medes was bounded with Mount Bikni, which modern scholars traditionally identified with Mount Damavand, but in recent decades some scholars tend to identify it with Mount Alvand near Hamadan, where the capital of the Medes is supposed to be located.
The very existence of a Median empire is questioned by modern scholars. It is being increasingly argued that such a political entity even if existed, must have been merely a political aliance among highland neighbors of Assyrians,  such as Urartu in southeastern Anatolia, Sagartians in modern northern Iraq, and the actual Medians in the area between what is today Hamadan-Kirmanshah in cental Zagros. Neither cuneiform sources nor archaeological evidence nor biblical accounts  support the historiography provided by Herodotus, who claimed there existed a Median empire.
Although Herodotus credits “Deioces son of Phraortes” (probably c. 715) with the creation of the Median kingdom and the founding of its capital city at Ecbatana (modern Hamadan), it was probably not before 625 BC that Cyaxares, grandson of Deioces, succeeded in uniting into a kingdom the many Iranian-speaking Median tribes.
According to Herodotus, the conquests of Cyaxares the Medes were preceded by a Scythian invasion and domination lasting twenty-eight years (under Madius the Scythian, 653-625 BC).  The Medes tribes seem to have come into immediate conflict with a settled state to the West known as Mannae, allied with Assyria. Assyrian inscriptions state that the early Medes rulers, who had attempted rebellions against the Assyrians in the time of Esarhaddon and Ashur-bani-pal, were allied with chieftains of the Ashguza (Scythians) and other tribes — who had come from the northern shore of the Black Sea and invaded Asia Minor. The state of Mannae was finally conquered and assimilated by the Medes in the year 616 BC.
In 612 BC, Cyaxares conquered Urartu, and in alliance with Nabopolassar (who created the Neo-Babylonian Empire), succeeded in destroying the Assyrian capital, Nineveh, in 612 BC, and by 606 BC, the remaining vestiges of Assyrian control. From this point, the Medes king ruled over much of northern Mesopotamia, eastern Anatolia and Cappadocia. His power was a threat to his neighbors, and the exiled Jews expected the destruction of Babylonia by the Medes (Isaiah 13, 14m 21; Jerem. 1, 51.).
When Cyaxares attacked Lydia in the Battle of Halys, the kings of Cilicia and Babylon intervened and negotiated a peace in 585 BC, whereby the Halys River was established as the Medes' frontier with Lydia. Nebuchadrezzar of Babylon married a daughter of Cyaxares. Cyaxares' son, Astyages (584 BC - 550 BC), went to war with the Babylonian king Nabonidus. An equilibrium of the great powers was maintained until the rise of the Persians under Cyrus the Great.
In 553 BC, Cyrus the Great, King of Persia, rebelled against his grandfather, the Mede King, Astyages son of Cyaxares; he finally won a decisive victory in 550 BC resulting in Astyages' capture by his own dissatisfied nobles, who promptly turned him over to the triumphant Cyrus.
After Cyrus's victory against Astyages, the Medes were subjected to their close kin, the Persians. In the new empire they retained a prominent position; in honor and war, they stood next to the Persians; their court ceremony was adopted by the new sovereigns, who in the summer months resided in Ecbatana; and many noble Medes were employed as officials, satraps and generals. Interestingly, at the beginning the Greek historians referred to the Achaemenid Empire as a Median empire.
After the assassination of the usurper Smerdis, a Mede Fravartish (Phraortes), claiming to be a scion of Cyaxares, tried to restore the Mede kingdom, but was defeated by the Persian generals and executed in Ecbatana (Darius I the Great in the Behistun inscr.). Another rebellion, in 409 BC, against Darius II (Xenophon, Hellen. ~. 2, 19) was of short duration. But the Iranian tribes to the north, especially the Cadusii, were always troublesome; many abortive expeditions of the later kings against them are mentioned.
Under Persian rule, the country was divided into two satrapies: the south, with Ecbatana and Rhagae (Rey near modern Tehran), Media proper, or Greater Media, as it is often called, formed in Darius I the Great's organization the eleventh satrapy (Herodotus iii. 92), together with the Paricanians and Orthocorybantians; the north, the district of Matiane (see above), together with the mountainous districts of the Zagros and Assyria proper (east of the Tigris) was united with the Alarodians and Saspirians in eastern Armenia, and formed the eighteenth satrapy (Herod. iii. 94; cf. v. 49, 52, VII. 72).
When the Persian empire decayed and the Cadusii and other mountainous tribes made themselves independent, eastern Armenia became a special satrapy, while Assyria seems to have been united with Media; therefore Xenophon in the Anabasis always designates Assyria by the name of "Media".
Following Alexander's invasion of the satrapy of Media in the summer of 330 BC, he appointed as satrap a former general of Darius III the Great named Atropates (Atrupat) in 328 BC, according to Arrian. In the partition of his empire, southern Media was given to the Macedonian Peithon; but the north, far off and of little importance to the generals squabbling over Alexander's inheritance, was left to Atropates.
While southern Media, with Ecbatana, passed to the rule of Antigonus, and afterwards (about 310 BC) to Seleucus I, Atropates maintained himself in his own satrapy and succeeded in founding an independent kingdom. Thus the partition of the country, that Persia had introduced, became lasting; the north was named Atropatene (in Pliny, Atrapatene; in Ptolemy, Tropatene), after the founder of the dynasty, a name still said to be preserved in the modern form 'Azerbaijan'.
The capital of Atropatene was Gazaca in the central plain, and the castle Phraaspa, discovered on the Araz river by archaeologists in April 2005.
Atropatene is that country of western Asia which was least of all other countries influenced by Hellenism; there exists not even a single coin of its rulers. Southern Media remained a province of the Seleucid Empire for a century and a half, and Hellenism was introduced everywhere. Media was surrounded everywhere by Greek towns, in pursuance of Alexander's plan to protect it from neighboring barbarians, according to Polybius (x. 27). Only Ecbatana retained its old character. But Rhagae became the Greek town Europus; and with it Strabo (xi. 524) names Laodicea, Apamea Heraclea or Achais. Most of them were founded by Seleucus I and his son Antiochus I.
In 221 BC, the satrap Molon tried to make himself independent (there exist bronze coins with his name and the royal title), together with his brother Alexander, satrap of Persis, but they were defeated and killed by Antiochus the Great. In the same way, the Mede satrap Timarchus took the diadem and conquered Babylonia; on his coins he calls himself the great king Timarchus; but again the legitimate king, Demetrius I, succeeded in subduing the rebellion, and Timarchus was slain. But with Demetrius I, the dissolution of the Seleucid Empire began, brought about chiefly by the intrigues of the Romans, and shortly afterwards, in about 150, the Parthian king Mithradates I conquered Media (Justin xli. 6).
From this time Media remained subject to the Arsacids or Parthians, who changed the name of Rhagae, or Europus, into Arsacia (Strabo xi. 524), and divided the country into five small provinces (Isidorus Charac.). From the Parthians, it passed in 226 to the Sassanids, together with Atropatene.
The revival of Zoroastrianism, enforced everywhere by the Sassanids, completed this development. Atropatene, already center of the fire cult during Parthian times (see Takht-i-Suleiman) now became the site of one of the legendary Great Fires. Under the patronage of Kartir, the 'priest of priests' of the early Sassanid kings, Arsacia/Rhagae advanced to become one of the two (the other being Ishtakhr, ancestral seat of the Sassanid priest-kings) centers of the Zoroastrian priesthood.
The name of Ariana is further extended to a part of Persia and of Media, as also to the Bactrians and Sogdians on the north; for these speak approximately the same language, with but slight variations.
– Geography, 15.8
Words probably of Mede origin appear in various other Iranian dialects, including Old Persian. For example, Herodotus mentions the word Spaka (dog), still found in Iranic languages such as Talyshi. Other words also thought to be of Mede origin (I.M Diakonoff, Medes) include
An Armenian manuscript from the 15th century which was probably copied from a much older work contains a Christian prayer in seven languages, one of them called "the Median language". The "Median language" in this prayer is in a Northern Kurdish (Kurmanji) dialect and may constitute the earliest record of Kurdish. The orientalist Vladimir Minorsky, an expert on Kurds, claimed that the basic unity of the Kurdish language derived from a single language and suggested that these might have been the Medes. Gernot Windfurh also adds that "The majority of those who now speak Kurdish most likely were formerly speakers of Median dialects".
The Medes are sometimes considered by Kurdish nationalists to be one of the ancestors of the Kurds based on linguistic and geographic claims. This conjecture is, however, challenged by other scholars who consider central Iranian dialects, mainly those of Kashan area and Tati as the only direct offshoots of Median language.. Moreover, although some medieval Armenian authors refer to Kurds as mark(Medians) or azgn marac(the tribe of the Medians), this is considered as part of a literary tradition of identifying modern ethnic groups with the unrelated ancient people. Moreover linguistic evidence shows the ancestor of the Kurds lived to the south of the Medes and departed from the South to the North.
Bruno Genito, 1986, The Medes: a Reassessment of the Archaeological Evidence, East & West, 36, Nos. 1-3, pp. 11-83. Rome.
Bruno Genito, 1995, The Material Culture of the Medes: Limits and Perspectives in the Archaeological Research,Un Ricordo che non si spegne, Scritti di docenti e collaboratori dell'Istituto Universitario Orientale di Napoli in memoria di Alessandro Bausani, pp. 103-118. Napoli
Bruno Genito, 2005 The Archaeology of the Median period: an outline and a research perspective, The Iron Age in the Iranian World (17- 20 November 2003) Ghent, Ghent University and the Royal Museums for Art and History, Brussels, Iranica Antiqua, 40, 315-340. Ghent.
M. R. Izady, "Are Kurds Descended From the Medes?" http://www.kurdistanica.com/?q=node/78