How to pronounce“millennian”in English

know gravitational wells will build societies and in uh you know O'Neal like spheres and and Humanity will move out into the cosmos and probably meet othersocieties that have done the same in millennian eon's past something very interesting has happened over the last 100 years thatpeople don't think about which is that the Frontiers that we have have started to shrink and disappear it used to be that 100 or 150 years ago if