Simply enter the YEAR, regardless of the date or month. E.g. : If the answer is 19 846 B.C., write : -19846
N.B. I do not claim to include all major events. Some answers are obvious and some are strickly for history geeks. Bare in mind that this is from the perspective a western millenial history/geography enthusiast. Try not to cheat and, more importantly, have fun!