Every existence is recorded in your soul, which again sits next to the heart and it is through the soul you access Creator and your many expressions within Creation. Accessing this and having this knowledge is a threat to your ego, who believes it is a body and personality, and the herd or social consciousness.
We are all fractals of Creator, as you expand in awareness and consciousness your identity expands and takes in your other identities on other planes and dimensions some existing simultaneously. This includes lives in other dimensions, in other civilizations, some very advanced. As you expand further you realize it is all you as every enlightened Master, Saint and Sage have said throughout time. The whole universe lies within you.