Landmarks:

• 1995: Exposed in OOPSLA95 by Ken Schwaber and Jeff Sutherland.
• 2001: "Agile Software Development with Scrum", a book by Ken Schwaber and Mike Beedle
• 2009: Scrum guide

Flavors:

• LargE Scale Scrum (LeSS)
• Scaled Agile FramEwork (SAFe)