Assyria was a major ancient Mesopotamian civilization that existed from the 21st to 7th centuries BC which conquered and administered most of West Asia from the Assyrian heartland in Upper Mesopotamia. Assyria is called the first true military superpower in human history, and pioneered major inventions and advancements in the first libraries and large-scale preservation and accumulation of knowledge, statecraft, centralised government, bureaucracy, warfare, military organisation, propaganda, art, and architecture. Assyrian imperial history spans the early Bronze Age to the late Iron Age, from its beginning as small Akkadian settlements in northern Mesopotamia to its zenith and collapse as the largest empire to date at the time, and is typically divided into the Early Assyrian, Old Assyrian, Middle Assyrian, Neo-Assyrian, and post-imperial periods. The Assyrian people survive to this day and continue to live and practice their culture in their ancient heartland and in the diaspora.