The name "Persia" (in ancient persian: Pārsa) has been for a long time used to refer to the nation of modern Iran, their own people and own ancient empires. It is defined as "Great Persia" the territory that had a significant cultural influence and historical importanc; this includes not only Iran, but also the current republics of Afghanistan, Azerbaijan, Tajikistan, the regions of the Caucasus, western Asia, central Asia and parts of southern Asia, until India and China. It has been ruled from the 6th century BC to the 7th century AD by various imperial dynasties, such as the Achaemenids, the Macedonians, the Seleucids, the Parthians, and the Sasanians, up to the Islamic rising and the Arab Caliphates. Around 550 BC King Cyrus II of Persia, known as Cyrus the Great, founded the Achaemenid dynasty. Between 522 and 486 BC King Darius I brought the Empire to its greatest extension establishing a precise administrative and financial structure, dividing it into satrapies (Persian provinces). The decline of the Empire occurred in 330 BC with the defeat of Darius III by Alexander the Great. The empire of Alexander shattered after his death and one of his general, Seleucus I, seized part of it. Thus the Seleucid dynasty began. This dynasty gradually lost the control of Persia and around 247 BC the Arsacid dynasty conquered Partia and founded the Parthian Empire. In 224 AD, following the fall of the Parthian Empire, Ardashir I established the Sasanian empire. It was the last pre-Islamic Persian empire. In fact, it was conquered by Rashidun Caliphate (one of the firsts Islamic states). Several cities continued to resist against the Islamic authority, but around 651 AD most of its territory was annexed to the Islamic caliphate, thus completing the fall of this empire.