Historically, Iran was commonly referred to as "Persia" in the Western world.[9] Likewise, the modern-day ethnonym "Persian" was typically used as a demonym for all Iranian nationals, regardless of whether or not they were ethnic Persians. This terminology prevailed until 1935, when, during an international gathering for Nowruz, the Iranian king Reza Shah Pahlavi officially requested that foreign delegates begin using the endonym "Iran" in formal correspondence. Subsequently, "Iran" and "Iranian" were standardized as the terms referring to the country and its citizens, respectively. Later, in 1959, Pahlavi's son Mohammad Reza Pahlavi announced that it was appropriate to use both "Persia" and "Iran" in formal correspondence.[10] However, the issue is still debated among Iranians.[11] A variety of scholars from the Middle Ages, such as the Khwarazmian polymath Al-Biruni, also used terms like "Xuniras" (Avestan: Xvaniraθa-, transl. "self-made, not resting on anything else") to refer to Iran: "which is the center of the world, [...] and it is the one wherein we are, and the kings called it the Iranian realm."[12] History Main article: History of Iran Further information: Timeline of Iranian history Antiquity Further information: Medes and Indo-Iranians Chogha Zanbil is one of the few extant ziggurats outside of Mesopotamia and considered the best-preserved example in the world. Iran is home to one of the world's oldest continuous major civilisations, with historical and urban settlements dating back to 4000 BC.[13] The western part of the Iranian plateau participated in the traditional ancient Near East with Elam (3200–539 BC), and later with other peoples such as the Kassites, Mannaeans, and Gutians. The Median dynasty ruled the earliest Iranian state.[14][15][16] In 612 BC, Cyaxares and the Babylonian king Nabopolassar invaded Assyria and destroyed Nineveh, the Assyrian capital, which led to the fall of the Neo-Assyrian Empire.[17] The Medes later conquered and dissolved Urartu as well.[18][19][20] Achaemenid Empire Main article: Achaemenid Empire The Achaemenid Empire at its greatest extent The Achaemenids united all Persian tribes under Cyrus I's son Cambyses I. Under Cambyses I's son, Cyrus II, the Achaemenids defeated the Medes and established the Achaemenid Empire,[21] the largest ever Iranian state.[20] Cyrus II conquered the Lydian and Neo-Babylonian empires, creating an empire far larger than Assyria. His comparatively benign policies helped to reconcile his subjects to Persian rule, prolonging the duration of the empire. The Persian king was also known as "King of Kings", "Megas Basileus" (Greek: xšāyaθiya xšāyaθiyānām), and "Cyrus the Great." Cyrus's son, Cambyses II (r. 530–522 BC), conquered the last major power of the region, ancient Egypt, causing the collapse of the Twenty-sixth Dynasty of Egypt. After the death of Cambyses II, Darius I (r. 522–486) ascended the throne by overthrowing the Achaemenid monarch Bardiya. Darius' first capital was at Susa, and he started the building program at Persepolis. He improved the extensive road system, and during his reign the first recorded mentions are made of the Royal Road, a highway from Susa to Sardis.[22] In 499 BC, Athens supported a revolt in Miletus, resulting in the sacking of Sardis. This led to the Greco-Persian Wars, which lasted the first half of the 5th century BC. In the First Persian invasion of Greece, Persian general Mardonius re-subjugated Thrace and made Macedon a full part of Persia.[23] Darius' successor Xerxes I (r. 486–465) launched the Second Persian invasion of Greece. At a crucial moment in the war, about half of mainland Greece was overrun by the Persians, including territories to the north of the Isthmus of Corinth.[24][25] This was reversed by a Greek victory following the battles of Plataea and Salamis, during which Persia lost its footholds in Europe, and withdrew from it.[26] The empire entered a period of decline. From 334 BC to 331 BC, Alexander the Great defeated Darius III (r. 336–330 BC) in the battles of Granicus, Issus and Gaugamela, swiftly conquering the Achaemanid Empire by 331 BC. Alexander's empire broke up after his death, and Alexander's general, Seleucus I Nicator, tried to take control of Iran, Mesopotamia, and later Syria and Anatolia. His empire was the Seleucid Empire. The Parthian and Sasanian Empires Main articles: Parthian Empire and Sasanian Empire The Arsacids of Parthia,[27] initially Seleucid vassals,[28] originated as leaders of the Iranian[e] Parni tribe in the northeastern steppes.[31] The Parthians gradually challenged Seleucid rule over Iran, eventually securing control through the 142 BC conquest of Babylonia.[27][32] Although fighting continued, the death of Antiochus VII Sidetes in 129 BC marked the collapse of the Seleucid Empire,[32] which then lingered on as a rump state in Syria until conquered by the Roman Empire in the 60s BC.[27] The Sasanian Empire at its greatest extent c. 620, under the reign of Khosrow II The Parthian empire endured for five centuries, but civil wars destabilized it. Parthian power evaporated when Ardashir I revolted against the Arsacids and killed their last ruler, Artabanus IV, in 224 AD. Ardashir established the Sasanian Empire, which ruled Iran and much of Near East before the Muslim conquests of the 7th century AD.[33] At their zenith, the Sasanians controlled all of modern-day Iran and Iraq and parts of the