When the Turkish Empire in the region disintegrated - consumed in the desert storms of the Great War - Britain and France were still, just about, major imperial powers.
The blood of a lost generation of young men and the riches built up over centuries had been poured into a narrow strip of European land on the Western Front, but in the Old World there were no territorial spoils to be had.
The Middle East though was different.
With the Turks defeated in Jerusalem and Damascus and Sinai and Gaza there was a new world to be made.
Britain, mandated by the League of Nations to govern the Holy Land, could set about honouring its commitment to the Jews of the world to build a national home for them in Palestine - probably not guessing that the issues surrounding the promise would remain a potent source of violence and discord a century later.
It was a moment of cataclysmic global upheaval and new nation states were formed like new islands thrown up by an undersea volcanoes: Jordan and Iraq in the British sphere of influence and Syria and Lebanon in the French.
In that age of empires no-one questioned the right of the Europeans to draw new borders to parcel up the old world - at least no-one the Europeans would have listened to.
The Sykes-Picot agreement is a secret understanding concluded in May 1916, during World War I, between Great Britain and France, with the assent of Russia, for the dismemberment of the Ottoman Empire.
The agreement led to the division of Turkish-held Syria, Iraq, Lebanon, and Palestine into various French and British-administered areas. The agreement took its name from its negotiators, Sir Mark Sykes of Britain and Georges Picot of France.
Some historians have pointed out that the agreement conflicted with pledges already given by the British to the Hashemite leader Husayn ibn Ali, Sharif of Mecca, who was about to lead an Arab revolt in the Hejaz against the Ottoman rulers on the understanding that the Arabs would eventually receive a much more important share of the territory won.
Why border lines drawn with a ruler in WW1 still rock the Middle East
In recent years of course those desert storms have begun to rise again and the structures built in that last great time of change are creaking in the wind.
Syria is consumed in the fires of civil war and it is hard to see how it will emerge again as a unitary state.
Next door in Lebanon - still traumatised by its own long years of conflict - a fragile tradition of co-operation between different religious communities just about hangs together.
The Kurds, Sunnis and Shia gathered together in the single entity of Iraq by the British may ultimately choose in the future to separate.
The old order lasted for almost exactly 100 years - one wonders if that is more or less time than its Anglo-French architects Sykes and Picot envisioned.
There has been no global cataclysm on the scale of the Great War to provide the catalyst for the changes which are already under way.
But we got a feel for some of the forces that will shape the new order in Vienna this week when the world's great powers - the UN Security Council plus Germany - struck a deal with Iran.
The talks were convened of course to deal with Iran's nuclear ambitions - and so they did.
But they were a kind of acknowledgement too of Iran's status as a regional power - a sense that in effect nothing can be settled in the modern Middle East without the Iranians.
Iran after all is the main force propping up the faltering Syria regime of Bashar al-Assad, and it is using Hezbollah, the militia it founded and funded in neighbouring Lebanon to bear the brunt of the fighting.
Iranian-backed Shia militias have been fighting in Iraq against Sunni extremists - often filling vacuums left by the country's armed forces.
The Houthi rebels in Yemen too are part of this Iranian regional movement.
Iran is the great power in the world of Shia Islam, just as Saudi Arabia would see itself as the leader of those who follow the Sunni tradition.
There are plenty of small wars in which their proxy armies fight each other in what sometimes feels like a looming regional confessional conflict.
America is still a great power in the Middle East, of course, but it is not the power it was - not least because it would find it hard to say what its preferred outcomes would be in this current age of conflict beyond an apparently hopeless search for stability.
And these are confusing times.
America wants for Syria the kind of regime change that Iran is hell-bent on stopping but in Iraq both find themselves fighting the barbarous extremists of the so-called Islamic State.
The problem in the Middle East is that its perfectly possible for my enemy's enemy to be my enemy.
This was a week of change though.
Once the US and Iran glared at each other across a chasm of values:  where the Iranians saw themselves as champions of Shia communities and exporters of revolution the Americans saw only sponsorship of terrorism.
That may now begin to change although we don't know how far or how fast that change will go.
Through the gloom of the current desert storms it is hard to know for sure what sort of Middle East will eventually emerge - but it is already clear that one of the strongest winds blowing in the region blows from Iran.
The last time an old order collapsed in the Middle East it seemed obvious who should be invited to construct a new one.