Iran The history of Iran has been intertwined with the history of a larger historical region, comprising the area from the Danube River in the west to the Indus River and Jaxerates in the east. Iran is home to one of the world's oldest continuous major civilizations, with historical and urban settlements dating back to 4000 BC. The Medes unified Iran as a nation and empire in 625 BC. The Acheamenid Empire (550–330 BC) was the first of the Iranian empires to rule from the Balkans to North Africa and also Central Asia. They were succeeded by the Seleucid Empire, Parthians and Sassanid’s which governed Iran for almost 1,000 years. The Islamic conquest of Persia (633–656) ended the Sassanid Empire and was a turning point in Iranian history. Islamicization in Iran took place during 8th to 10th century and led to the eventual decline of the Zoroastrian religion in Persia. After centuries of foreign occupation and short-lived native dynasties, Iran was once again reunified as an independent state in 1501 by the Safavid dynasty which established Shi'a Islam as the official religion of their empire, marking one of the most important turning points in the history of Islam. Iran had been a monarchy ruled by a shah, or emperor, almost without interruption from 1501 until the earliest archaeological artifacts in Iran, like those excavated at the Kashafrud and Ganj Par sites, attest to a human presence in Iran since the Lower Paleolithic era. The 1979 Iranian revolution, when Iran officially became an Islamic Republic on 1 April 1979. Neanderthal artifacts dating back to the Middle Paleolithic period have been found mainly in the Zagros region at sites such as Warwasi and Yafteh Cave. Iran is not known to currently possess weapons of mass destruction (WMD) and has signed treaties repudiating the possession of weapons of mass destruction including the Biological Weapons Convention, the Chemical Weapons Convention, and the Nuclear Non-Proliferation Treaty (NPT). Iran has first-hand knowledge of WMD effects—over 100,000 Iranian troops and civilians were victims of chemical weapons during the 1980s Iran–Iraq War. The IAEA has confirmed the non-diversion of declared nuclear material in Iran, but has also said it "needs to have confidence in the absence of possible military dimensions to Iran’s nuclear programme. In November 2007, a United States National Intelligence Estimate asserted with “high confidence” that Iran, contrary to American and Israeli accusations, was not building nuclear weapons. Iranian motives for crafting such a device would obviously have significant implications for determining what policies should be pursued by the rest of the international community. Yet, this appears to be the least discussed aspect of the issue, at least by media personalities, politicians and presidential candidates. Many seem to have concluded, perhaps prematurely, that if successful, Tehran’s acquisition of nuclear weapons will constitute an immediate and existential threat to the state of Israel. I believe that the United States should get involved. Nuclear weapons could kill millions of people. I feel as though America should not be involved in Iran. It should be more important to us that we take care of our problems here in the United States before we stick our faces in other countries problems. A lot of the times when we become involved it makes matters worse, and we should not put ourselves in the middle all the time.