Here's a beast that is filled with relational ladders:

Logic-Civilizations-0.gif
I got this far, but no further:

Logic-Civilizations-1.jpg
Anyone see the next logical step?

I converted the ladders into inequalities to try and help, but I don't see it. Call the Columns A, B, C and the first row D. I use (+1) and (+2) to mean that the inequality is the same as saying C5 + 1 = C1. I use the inequality sign as a mental reminder of what I'm doing. I use 1 and 2 to indicate increments of position, rather than the actual value of years.

A2 < B4

C5 <(+1) C1

C5 <(+1) A3 (At this point, we know that A3 = C1)

B1 <(+1) B5

A4 <(+2) C4

Normally, I would pair up these inequalities to see if any of them form logical relationships. However, I get nothing through these pairings except that A3 = C1