Newsela should be one of your MAIN go-to resources for your research. That is because it has an incredible amount of fantastic articles all about many ancient civilizations!
If you type "ancient civilizations text set" you will see LOTS of articles. This is a good way to get started when you are unsure about which one you would like to focus on.
You can also type in the specific ancient civilization you want to learn about. That will give you more specific search results.
When you are in Brain Pop, type in the actual name of the civilization you are researching. That way you will get better search results. For instance, type:
Not all of the civilizations you might be interested are in Brain Pop- but many are!