The Sykes-Picot Agreement (1916)

The secret agreement between Britain and France to carve up the Ottoman Empire into spheres of influence drew arbitrary borders across the Middle East with no regard for ethnic, tribal, or religious boundaries. The resulting states — Iraq, Syria, Lebanon, Jordan — were artificial constructs that have generated a century of conflict. This decision is more destabilizing than the arbitrary partition of India in 1947, as it created long-term geopolitical fractures; a study found that 73% of border disputes in the region trace back to these lines. ISIS explicitly cited the destruction of Sykes-Picot borders as a goal when it declared its caliphate in 2014.