http://en.wikipedia.org/wiki/Vedic_timeline http://en.wikipedia.org/wiki/Category:Four_Yugas
http://www.vedanet.com/index.php?option=com_content&task=view&id=129
Good question.
I don't really know. The first stage would be to see what those numbers might correspond to in the sky. Generally, I have been looking at much shorter time-frames.
The longest cycle I have encountered so far is (one fifth of) 25 800 years (the cycle of precession of the equinoxes) and at this point I can not really justify this--because I do not have an explanation for the one fifth. And the longest cycle that I have come across that is sure is a 112-year eclipse cycle (actually 1385 months) in an account of the markings on a brass bowl recovered from Arabia and dating from Mohammedian times or possibly earlier (brass is hard to date). The 56-year cycle of the Dragon against the year can be confidently adduced to the ring of hollow stones at Stonehenge. This is not an eclipse cycle, but is instead relevant to the elevation of the Moon's path in the sky.
On the other hand, while I may know the meaning in the sky, I won't know the meaning on the ground! So I definitely miss part of what is going on.
One of my friends is studying mythological structures, and sometimes our results dovetail perfectly. But that is a study that is even murkier than what I am doing. At least to me. ;)
