It began when the representatives of the Third Estate chose a new king, created the National Assembly and pledged to create a Constitution.
It officially began with the storming of the Bastille on July 14th, 1789
The question is kinda lacking. Probably, it has choices to make the question answerable.
Answer:
They may base events from history on periods of time using a certain theme, so to say. This way, it allows them to organize information in a chronological order and base events on how severe they were and what led up to the most significant event in that time period, because a turning point is basically the most important part in a time period which initiated change. This also emphasizes on the importance of transitions.
