On Mashiach's Nevuah

Temurah 16A

"The day that Moshe was going to die, he said to Joshua, ask me anything you want. He said, "I wouldn't forget a word you said". After he died, Joshua forgot 300 halachot and discovered 700 uncertainties, and the Jews were ready to kill him. G-d said, "I can't tell them to you"... eventually Otniel ben Kenaz derived them through his logic."

There are 300 halachot mentioned in the Zohar pertaining to the world of Tohu concerning the phrase "and the name of his wife was Meheiteval". I've read about those.

So, the 700 uncertainties must pertain to Hadar, the 8th king and the last one preceding a king in Yisrael.

And, the first 7 kings represent unstable chaos, Hadar represents stable chaos and then comes the world of tikun and a king in Yisrael.

On the other hand, why forget? Interestingly, there are 4 sets of "300 halachot":

# Three hundred halachot concerning "a mighty bright spot."
# Three hundred halachot concerning "you shall not let a sorceress live."
# Three hundred halachot concerning "the tower soaring in air."
# Three hundred halachot concerning "and the name of his wife was Meheitavel."

Mashiach's Prophecy & The Secret Of Splitting The River