A government or state ruled by two equal authorities or leaders; a system of dual rule or two-person leadership.
From Greek 'di-' (two) + 'archos' (ruler). Coined in political theory to describe shared governmental authority, distinct from monarchy (one ruler) or anarchy (no ruler).
Sparta is the most famous diarchy in history—two kings ruled together with built-in checks and balances, which made it harder for one person to become a tyrant!
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