The most significant nation to be affected was, of course, the Arab Republic of Egypt. It is home to more than 80 million people, bridges North Africa and Asia and is a major power in the Mediterranean, among Arab nations and in the Muslim world.
Transition from the presidency of Hosni Mubarak was never going to be straightforward. The road from dictatorship to some form of democracy is at best rocky wherever and whenever it takes place.
Usually, there are obstacles, delays and false starts, and the optimism of the early days is often dashed in one way or another.
Yesterday was one of those occasions for many in Egypt to revel in a bout of positive thinking. The Supreme Constitutional Court, still stacked with previous regime appointees, ruled last year's elections invalid and dissolved Parliament, and the military - which controls the current government - has made it clear the new president would have limited powers.
Nevertheless, its favoured candidate was defeated in the presidential election by the Muslim Brotherhood's Mohamed Morsy, and the military has, at least for now, allowed the vote to stand.
Predictions on what happens next seem to depend, in large part, on the outlook of observers. Pessimists and sceptics cannot believe the army and the current establishment will give up power, economic control and perks. They doubt whether the Muslim Brotherhood and the new president can live up to - or even believe in - the conciliatory words about a government of unity and of peace.
What will happen if a stand-off develops between the army and the Brotherhood's supporters?
Can masses on the streets again prove persuasive?
Will sectarian differences, always ripe for manipulation by the cynical and ruthless, be exploited?
The West, which has so regularly backed Middle East dictators because of stability they were thought to bring, because of their oil, and because of their role as bulwarks against militant Islam, is ambivalent about many of the developments. It must be seen to support moves towards democracy, even when Muslim parties win, something reflected in White House statements yesterday calling on Egypt to remain "a pillar of regional peace".
Britain's foreign minister, William Hague, cautiously welcomed Mr Morsy's victory, saying it was important the new government stood for national unity and reconciliation, to build bridges across Egyptian society and to uphold human rights, notably for women and the Christian minority.
As the world holds its breath to see what transpires, optimists see some hope that the Muslim Brotherhood and military have shown conciliatory signs and attitudes. The Brotherhood, which was also the largest party in the dissolved elections, will have to reach out to reassure minorities, the secular middle classes and youthful educated revolutionaries in deed as well as word. It will have to corral its extremists and jockey for position vis-a-vis the military with care. As one military source put it: "The world is now watching the new president."
The hope is that, as in Turkey, the boundaries of democracy can be extended and the control of the military can, over time, wither. If the Brotherhood is sensible, it will know it has to play a long game and that, given the relatively modern nature of Egyptian society and economy, the moderate path will be the most effective, the most realistic and the hardest for the army to resist. The journey to avoid provoking the military will be precipitous but just might be possible.
A parallel concern is the attitude of the generals. It is always hard to give up entrenched privileges. Yet that is what the military is going to have to do if the Egyptian revolution is to have lasting substance and if mass protests and probable violence and upheaval are to be avoided.
