That time was a critical time in our history because that was when man began to start evolving from hunter-gathering to farming/agriculture. Many civilizations that stayed in hunting-gathering could not grow their civilization and traditions (because agriculture led to a boom in population) therefore some died out where some civilizations (Egypt and China) adapted to agriculture early and their land was suited for agriculture, helping their civilization to sustain for a longer period of time.
In 1968, during the Democratic National Convention held in Chicago, governors gathered to discuss, once again, the future of the U.S. involvement in the Vietnam War.
There were two opposing groups. On the one hand, the ones who didn't want the U.S. to continue participating in the War, led by Eugene McCarthy. On the oher hand, the winning side, who supported the war, led by Hubert Humphrey.
As a result, that same day outside the Convention, thousands of antiwar activists gathered to protest and to show their respect for McCarthy. But they were not alone, because Richard Dale, who was the Major of Chicago by then, deployed thousands of police officers to alleviate the situation. The event ended up in a complete disaster: people beating each other and getting hurt. Therefore, this episode is also known as "the Battle of Michigan"
Chebyshev's rule is a lower bound on the proportion of data that can be found within a certain number of standard deviations from the mean. If the distribution is roughly bell-shaped, the empirical rule, in general, provides better estimates than Chebyshev's rule.