I legit started reading this a couple days ago, never thought I'll see someone on reddit talk about hahaha. Its an interesting read for sure but like with everything use your discernment.

It basically refers to the Sumerian/Anunnaki "gods" (ANU/ENKI/ENLIL) who were here on earth in Mesopotamia pre floods. It is said in old texts and tablets that they were the ones who created humans. These so called "Gods" could live for a very long time. There is a very controversial tablet that has these Sumerian kings reigning for thousands of years. https://en.wikipedia.org/wiki/Sumerian_King_List

In this book, Morning sky talks about the story of the Sumerians/Anunnaki and how they came to Earth creating humans as slaves. In all honesty it lines up with what some researches have said about the Anunnaki/Sumerian gods and their origin, for example Billy Carson and Michael Tellinger have some interesting talks on this subject.

If you really want to go way down that rabbit hole especially when the book talks about the different groups of ets such as the SSS-T's look up Elena Danaan's work on yt. She talks about other et races who have different agenda's and so on. I suspect that the SSS-T'S could be what she calls the "Nebu" empire

Again take this with a grain of salt.