What Unites These Nations?

ASEAN says it wants to become a more robust organization with more “teeth.”   Think they can do it?  Maybe this is a clue:

The 10 leaders, whose members range from an absolute monarchy and military juntas to parliamentary democracies and one-party communist states, have agreed to start drafting a charter that would give ASEAN a legal basis for the first time since it was founded at the height of the Vietnam war nearly 40 years ago.

I wonder what unites those nations, beyond economic interests.  Economic associations are perfectly fine things, but taking the next step would seem to require a most unlikely  agreement on whom to bite.