sentence: World population begins to rise steadily.
sentences_before: The alphabet develops. Indo-Iranian migration onto the Iranian plateau and onto the Indian subcontinent saw the creation and use of the chariot. Chariot warfare and population movements lead to violent changes at the center of the millennium. New order emerges with Greek control of the Aegean and the rise of the Hittite Empire. The end of the millennium sees the start of the Iron Age.
sentences_after: By 1000 BC the population of the world reached nearly 50 million.
concept_name: world population
headings: 2nd millennium BC