Chapter 4: How it all began
Officially people trace the beginning of Agile to the publication of the Agile Manifesto in 2001. This was the result of the gathering of a small group of developers who met in the U.S. to define the Agile principles and fundamentals, ultimately reflected in the Manifesto.
But the reality is Agile's roots come from before that time, going as back as the 1950's to Japan and the U.S. where some of the core Agile concepts started to take form.