I believe I heard HaRav Yitzchak Breitowitz (but please don't quote me on this) say at some point that it's been shown that the concepts from Zohar date back to the 2nd temple period. I am not sure where this is from, so I'd like to ask: what time period do the concepts from Zohar date back to? Zohar has been accepted as one of the foundations of Jewish mysticism, but I'm curious as to what the scholarship says regarding its legitimacy and dating.
EDIT: Just to clarify, I'm not asking about when the Zohar was being written or when it was compiled, but whether the concepts in Zohar trace back to the 2nd Temple Period. I know that Rabbi Simeon ben Yohai in the second century is said to have written down the concepts of the Zohar, but he given the nature of the mysticism, it was likely something passed down in secret for generations (at least this is the way its taught I think). Therefore, he likely didn't create the important concepts, but merely formulated them and put them down if we are to believe this. From this, I'd like to know how long have the concepts that he formulated in Zohar been passed down for? When do they trace back to in their origin?