through Greek sources and used as an exonym for all of the Persian Empire for many years. Thus, especially in the Western world, the names Persia and Persian came to refer to all of Iran and its subjects. Some medieval and early modern Islamic sources also used cognates of the term Persian to refer to various Iranian peoples and languages, including the speakers of Khwarazmian, Mazanderani, and Old Azeri. 10th-century Iraqi historian Al-Masudi refers to Pahlavi, Dari, and Azari as dialects of the Persian language. In 1333, medieval Moroccan traveler and scholar Ibn Battuta referred to the Afghans of Kabul as a specific sub-tribe of the Persians. Lady Mary (Leonora Woulfe) Sheil, in her observation of Iran during the Qajar era, states that the Kurds and the Leks would consider themselves as belonging to the race of the "old Persians". On 21 March 1935, former king of Iran Reza Shah of the Pahlavi dynasty issued a decree asking the international community to use the term Iran, the native name of the country, in formal correspondence. However, the term Persian is still historically used to designate the predominant population of the Iranian peoples living in the Iranian cultural continent. History Persia is first attested in Assyrian sources from the third millennium BC in the Old Assyrian form , designating a region belonging to the Sumerians. The name of this region was adopted by a nomadic ancient Iranian people who migrated to the region in the west and southwest of Lake Urmia, eventually becoming known as "the Persians". The ninth-century BC Neo-Assyrian inscription of the Black Obelisk of Shalmaneser III, found at Nimrud, gives it in the Late Assyrian forms and as a region and a people located in the Zagros Mountains, the latter likely having migrated southward and transferred the name of the region with them to what would become Persis (Persia proper, i.e., modern-day Fars), and that is considered to be the earliest attestation to the ancient Persian people. The ancient Persians played a major role in the downfall of the Neo-Assyrian Empire. The Medes, another group of ancient Iranian people, unified the region under an empire centered in Media, which would become the region's leading cultural and political power of the time by 612 BC. Meanwhile, under the dynasty of the Achaemenids, the Persians formed a vassal state to the central Median power. In 552 BC, the Achaemenid Persians