The millennium is the seventh dispensation.

Innocence: From creation to the fall
Conscience: From the fall to the flood
Human Government: From the flood to Babel
Promise: From Babel to Mt Sinai
Law: From Mt Sinai to the cross
Grace: From the cross to the rapture

It will be the last age bfore eternity, the perfect
state when God will again be all in all as before
rebellion started in the universe.