You must write that tells the story or "legend" of how your civilization came to be. If you are writing it must be no shorter than three paragraphs and no longer than five. If you are making a short video it must be 3-5 minutes. You must name your civilization and give a glimpse of what type of society it is as you tell the story.

I am not going to give a actual story because I think that wouldn't help you in any way. This is why I will give you some tips. My teacher also assigned a similar task. (Hopefully it helps you...)

Explanation:

I think you could start with inspiration from how almost every civilization comes to be. Start near a water source or siblings get divided. The water could be water from "divine gods" to "the dead ancestors". The brothers getting divided could be like, "A long time ago, there was a war that struck all of the land..." and like the King could be slain in the war, but he had two sons. Or one son and one daughter or two daughters.

Then for the glimpse of society, you could state what kind of laws it has, the feudal system (RANKS), how the army is...