How do historians use turning points to better orginize information about the past

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.

tenochtitlan (also spelled tenochtitlán), located on an island near the western shore of lake texcoco in central mexico, was the capital city and religious centre of the aztec civilization. the traditional founding date of the city was 1345 ce and it remained the most important aztec centre until its destruction at the hands of the conquering spanish led by hernán cortés in 1521 ce, which led to the final collapse of the aztec empire.