When people think about Dimensions, they tend to believe that the highest the Dimension, the better it is, and the closest to GOD / Source we must be, but in fact, this is not true.
Dimensions have different frequencies, it is true. Frequency is an Electromagnetic Wave, the more the wave oscillates, the higher the Frequency and the Dimension are, but this does not mean that the Beings in that Dimension are aligned with the Source's Divine Plan, which is learning to give Immense Love to All that it is!
When we think about the whole picture of Creation, we see layers upon layers. One of these layers is the substrate of Creation, thus in the First Dimension. The First Dimension is Ether and it is Etheric. But First Dimension does not mean it is Bad, that the Second would be any better, because it is higher than the First, and the Third would be better than Second and so on… In fact, Ether is a substrate and all the codes of energy, life and matter were written upon it.
Through time, lots of things happened and lots of Wars took place through the Cosmos, Universes; Dimensions that altered the Original Order have caused distortions in Structures of Space-Time and so on.
Through Time some Species, some Inter-dimensional, learned how to write upon these Codes substrate and manipulated other Dimensions.
The Elite (which is Inter-dimensional anyway) was always very interested in manipulating Time, because this way they can perpetuate their game, they can go back and forward and even change events at their own will. One of the Species that are addicted to the Space-Time Matrix are the Dracos, who developed high Technology to manipulate the Space-Time Matrix, creating Synthetic Portals & so on.
In these Wars, through time they managed to take over some Dimensions. Remember that in all Dimensions there are Living Beings! Just because a higher Dimension has a higher Frequency, that does not mean it is better, nor that it has "Better Beings" living in it, or that they are good in all aspects. What happens on Earth is a Reflexion of what happens in higher Dimensions too. Good and Bad do not matter, they're a reflexion of this Game, that has been played over time, over eons.