Although these numbers are approximate, they still allow us to ask a question: why did history begin then, and not earlier, and not later?
History begins with writing. Before the introduction of writing, there is no history. From the times prior to writing, there are the findings of archeology and paleontology, but history itself is and requires written records.
Writing is a product of civilization. Civilization arises when human have excess production beyond what is needed for mere survival: extra time and extra materials.
Civilization arises on the basis of physical structures (buildings), agriculture, and the domestication of animals. Civilization requires at least a modicum of stability - physical, economic, political, military.
Of the various types of stability needed for civilization, physical stability is the most pressing.
At a certain point in time, the earth was not as physically steady as it is now. Tectonic plates, which now move only inches in a year, moved miles in the same timespan.
Volcanic activity, which is now rare, caused entire mountains to rise or fall in a single day.
The humans who lived during that time were unable to organize any lasting form of civilization.
One of the preconditions, then, which was necessary for history to begin was the physical calming and settling of the earth’s crust. Only with the increase of material steadiness could civilization begin.
That’s why history and civilization began when they did, and not earlier.
