Now, more than at any point in modern history, Iran and Saudi Arabia are squared off against each other as a race to consolidate influence nears a climax from Sana’a to Beirut and the tens of thousands of miles in between.
The standoff is seeing new ground conquered, previously unimaginable alliances being mooted and the risk of a devastating clash between two foes whose calculations had long been that shadow wars through proxies were safer than facing up directly.
The shift in approach has been led from Riyadh, where a new regime determined to put Saudi Arabia on an entirely different footing domestically, is also trying to overhaul how the kingdom projects itself regionally – and globally.
The ambitious, unusually powerful, crown prince, Mohammed bin Salman, has been given a mandate by his father, King Salman, to take on what the kingdom and its allies in the United Arab Emirates see as an Iranian takeover of essential corners of the Sunni Arab world.