alliance

同盟　—　Institutions

A promise of common action among states or cities.

Two-euro commemorative (ten years of Economic and Monetary Union)2009 Double Vereinsthaler (Southern Railway commemorative)1857 Belgian five-franc silver coin1869

⚠ Alliances to standardize currency can last longer than military alliances, or they can collapse just as easily. It depends on whether there is a mechanism to enforce them.