> And the fact that all lengths are multiple of 600

I know this must somehow explain the giant numbers but I'm still not sure how precisely.

Counting in base 60 would make for much smaller numbers, no ?

For example, the number 16 in base 2 is 1111. but in base 10 it is 16. Ergo smaller base, larger number, and vice versa.

So did you mean to say they counted in units that are made of 1/600 of our solar years? I think that would make more sense, putting their reigns between 31-72 years of our counting.