The 1st millennium BC, also known as the last millennium BC, was the period of time lasting from the years 1000 BC to 1 BC (10th to 1st centuries BC; in astronomy: JD – ). It encompasses the Iron Age in the Old World and sees the transition from the Ancient Near East to classical antiquity. World population roughly doubled over the course of the millennium, from about 100 million to about 200–250 million. Overview The Neo-Assyrian Empire dominates the Near East in the early centuries of the millennium, supplanted by the Achaemenid Empire in the 6th century. Ancient Egypt is in decline, and falls to the Achaemenids in 525 BC. In Greece, Classical Antiquity begins with the colonization of Magna Graecia and peaks with the conquest of the Achaemenids and the subsequent flourishing of Hellenistic civilization (4th to 2nd centuries). The Roman Republic supplants the Etruscans and then the Carthaginians (5th to 3rd centuries). The close of the millennium sees the rise of the Roman Empire. The early Celts dominate Central Europe while Northern Europe is in the Pre-Roman Iron Age. In East Africa, the Nubian Empire and Aksum arise. In South Asia, the Vedic civilization gives rise to the Maurya Empire. The Scythians dominate Central Asia. In China, the Zhou dynasty rules the Chinese heartland at the beginning of the millennium. The decline of the Zhou dynasty during Spring and Autumn period and the Warring States period sees the rise of such philosophical and spiritual traditions as Confucianism and Taoism. Towards the close of the millennium, the Han Dynasty extends Chinese power towards Central Asia, where it borders on Indo-Greek and Iranian states. Japan is in the Yayoi period. The Olmec civilization declines, and the Maya and Zapotec civilizations emerge in Mesoamerica. The Chavín culture flourishes in Peru. The first millennium BC is the formative period of the classical world religions, with the development of early Judaism and Zoroastrianism in the Near East, and Vedic religion and Vedanta, Jainism and Buddhism in India. Early literature develops in Greek, Latin, Hebrew, Sanskrit, Tamil and Chinese. The term Axial Age, coined by Karl Jaspers, is intended to express the crucial importance of the period of c. the 8th to 2nd centuries BC in world history. World population more than doubled over the course of the millennium, from about an estimated 50–100 million to an estimated 170–300 million. Close to 90%