The cultural development or Sumer and Elam ran parallel. A script was in use in Elam (Kerman) simultaneous to the first pictorial writing in Ur (3000 B.C.). Temple structures in both areas had the same ziggurat form, the man-made mountain reminiscent of their highland origins. Many cultic and religious habits were the same throughout Mesopotamia; the snake cult of Elam however was distinct and foreign.
Elam controlled the plain between the Zagros Mountains and the swamps of the two rivers as well as the entire Iranian Plateau to the great salt desert. This gave the Elamites great advantages, as suppliers of gold, timber, stone and other basic raw materials which had to be imported by the civilizations in the alluvial plain. At times, when the lowlands of Elam were overrun by invaders from Mesopotamia, indigenous Elamite dynasties recovered the loss after weathering the storm by withdrawing to the mountains. While dynasties and population groups in Mesopotamia changed drastically, Elam retained continuity.
Metallurgy and the introduction of the chariot introduced revolutionary changes. Dependence on horses and metals from the mountains of Iran and Eastern Anatolia grew, and control of the source was vital. Larger armies could be formed and greater distances covered. The spoils accrued by successful war became ever more luring.
The basic policy however remained the same and the cruelty displayed in the magnificent relieves of Khorsabad and Nineveh bears mute witness: heaps of bodies floating down river, burning cities, enslaved populations, beasts loaded with loot underscore the terror. The king is glorified for his prowess with the chariot and his skill in killing lions.
Two important changes occurred after 1000 B.C. The rivers pushed the land further out into the Persian Gulf and fused to form the Arvand Rood. The swamps receded down river. This changed and weakened the strategic position of Elam.
By 850 additional small tribal groups of Aryan stock, including Persians and Medes, infiltrated the mountains of Kurdistan and Fars, ringing Elam. The pattern of their nomadic life centered around herding of animals from the warm winter pastures on the fringes of the plain to the rich green meadows of the mountains in summer, thus avoiding the parched land and heat of the lowlands of Mesopotamia and Elam in summer.
Internecine strife between small tribal bands over migration routes, water-holes and better pastures prevented any large-scale concerted action. However, groups banded together to raid the trade caravans bringing goods to the plains. Occasionally small settlements were robbed. The association with established cultures of Urartu, Elam, Babylonia and Assyria affected tribal life but little. Tribal manpower however was used as levies in the armies and the naturally truculent tribesmen learned the finer arts of warfare.
The supply of horses and metals from the mountains was so crucial that the superpower of the day (800-600 B.C.), Assyria, was forced to take steps to protect its trade routes. Attempts were made to control the entire axis of the Mediterranean harbors and the mouth of the Persian Gulf. Great successes were achieved by Assyria under great leadership. It is known from the clay-tablet records, with details often filled in by archaeological excavations, that the Babylonians and Elamites formed a defensive union and prolonged war started. Assyria, after successfully attacking Egypt, launched a large-scale amphibian invasion with a substantial fleet through the head waters of the Persian Gulf on the shores of Elam. This invasion was repelled (698), but a new attack was mounted two generations later, when there was serious internal strife and conflict over the royal succession in Elam. The Elamites army with its Persian tribal levies was decisively defeated in the battle of the Ulai River (652). Shortly thereafter Babylon was invested, Elam completely destroyed (639) and the Chaldeans of Ur were pushed into the swamps.
This did not overcome Assyria’s problem with the Iranian mountain tribes, the roving Sumerians and Scythes and Medes, nor with the urbanized Urartians. The trade routes through Asia Minor remained insecure. Assyrian armies assaulted the mountains, roaming far and wide, through Kurdistan, Armenia, to Mount Ararat. They destroyed the cities of the established highland civilizations, weakening especially Urartu.
The tribes eluded them completely, fading into the mountains on the news of the arrival of any large army. Tribal life however was markedly changed. A tribal leader was elected, the migration routes controlled, internecine strife quelled. The destruction of the controlling forces of urban-agricultural Urartu and Elam liberated the tribal Persians and the Medes from many restrictions and the nomadic population and power grew by leaps and bounds. Great areas which were until that time under intense cultivation are still today nomadic grazing grounds, and the political problem created by the decline of Elamites power is still being felt. The tribal leaders now accepted the title of Kings. (It is important to note that the king always had to be of royal family. The fate of the tribe, however, is so important that it cannot be handed to just any member of the family. The best possible man is selected by consensus from several royal candidates. This explains the rather startling shifts in family relationship amongst the early Achaemenian kings).
Achaemenes had become king of the Persians just prior to the showdown between the Assyrians and Elamites (700). The Assyrian commander who destroyed Elam (639) met with Cyrus I in the area of today’s city of Behbahan and accepted his son as hostage. The Persians were biding their time. Their enlarged kingdom was temporarily divided between two grandsons of Achaemenes - Cyrus I and Ariaramnes - as kings, respectively, of Parsumash and Parsa.
Assyria had extended its power to the limits. The Chaldean kings of Sumer revitalized Babylon. A Babylonian and Medic coalition attacked Nineveh and Khorsabad and destroyed the royal Assyrian cities and Assyrian power (612). Neobabylonia expanded, opened the sea route through the Mediterranean, fruitlessly attacked Egypt but did not attempt to force the mountains where Cambyses, son of Cyrus I, had inherited the crowns of Parsumash and Parsa and reigned as King of Anzan (600-559).