What is important? (Chapter 6)

How do historians choose what is important or irrelevant. Strayer presents five ways that some historians use for criterions to evaluate the past:

1. Duration: The longest period in history should be the main focus.

2. Change: Then change that has happened to humans either directly or indirectly.

3. Population: the amount of humans occupying a certain region 

4. Influence: Religion and philosophies that have become important to us

5. Location: the location of historian and his or her audience.

I always wondered how authors/historians choose to insert certain facts, stories, etc in my textbook and now I know. I wouldn't say-- I understand them totally but I understand that their is a lot of facts, research in history and they are here to tell/share.