What time period do the concepts from Zohar date back to? Is it actually 2nd Temple Period?

Question

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?

Answer 1

Rabbi Dr. Samuel Belkin in his Midrashei Philon says that in particular Midrash HaNelam contains very close language to the language of Philo. He suggests that Philo is one of the sources for the teachings of the Zohar (המדרש הנעלם ומקורותיו במדרשים האלכסנדרוניים [The Midrash Ha-Ne'elam and Its Sources Among the Alexandrian Midrashim], Sura, vol. 3, pp. 25-92).

Philo predates the Rashbi and actually visited the Temple while it was still standing and functioning.

In other words, Rabbi Akiva, who taught the Rashbi, was transmitting, at least partially, the teachings of Philo ( AKA Yedidyah HaKohen) of Alexandria, one of the leaders of the Jewish community in Alexandria, Egypt who lived in the 1st century BCE.

Rabbi Belkin was the 2nd President of Yeshiva University and received his ordination from the Chofetz Chaim. He was a renowned expert in the writings of Philo.

There is a story I have seen that in the last trip by Professor Gershom Scholem to the United States, they met & discussed Rabbi Belkin’s conclusions about the Zohar. The story reports that Scholem conceded to Rabbi Belkin that his conclusions were likely correct.