Obviously our knowledge of much pre-modern history is less accurate and precise than our knowledge of periods with huge amounts of written records. I wonder what's the earliest event in history that we can date to the day, month or year? Off-hand, I know that Caesar was assassinated on March 15, 44BC, for example. How far back in human history can we continue to go and still know that event A happened on the ___ of ____ in the year ____?