For the better part of the last century, three Arab states — Egypt, Iraq and Syria — dominated Middle East politics in matters of war and peacemaking and shaped the region's relations with the great powers.

The kings of Jordan and Morocco — and, of course, Saudi Arabia (and the Persian Gulf states) when it came to oil — had their say too. But it was the three pseudo-republics, authoritarian military regimes really, that threw their collective weight around.

Not anymore. The changes sweeping the Arab world have injected new life and meaning into its politics. But that has also fundamentally undermined the capacity of the key Arab states to act decisively and coherently on the regional stage.

It's the new world of the non-Arabs — Iran, Israel and Turkey — that will now increasingly shape that stage for both good and ill. No matter how long it lasts, the eclipse of the Arabs will carry important consequences for the Middle East and the United States' interests there.

For decades, Egypt, Iraq and Syria, cooperating at times but competing for influence and power always, shaped the Arab world's policies toward East and West, drove the alliances and maneuvering in inter-Arab politics, determined what would and would not happen when it came to Israel, and carried out their own ambitions. These three republics and the men who dominated them became the face of the Arabs to the world.

Egypt held the key to peacemaking with Israel, Iraq to stability in the Persian Gulf and Syria to Lebanon. America would come to depend heavily on the first, go to war twice with the second and both court and try to check the ambitions of the third. With some exceptions, it was a world that had acquired a perverse kind of stability. The status quo was hardly perfect, but it was, particularly after the Iraq war and the demise of Saddam Hussein, relatively manageable for the Arabs and the West.

Now all of that is gone. Within a year — a stunningly inconsequential unit of time in the grand sweep of Middle Eastern history — these three Arab states have gone off line. In the case of Iraq, this has been in the works for some time now. Iraq is becoming a dysfunctional state marked by continuing violence and unable to create a legitimate political contract. Its Shiite-dominated regime and Sunni rivals will continue to wrangle at the expense of a functional and effective governance.

Egypt, preoccupied with its internal house and seeking a new-found independence from the United States, may want a more ambitious role in the region. But it probably will be unable to deliver. Its economy is in shambles. And its political system is locked in a competition between Islamists and the military, both of which seem to want influence without the real responsibilities of governance. A vacuum has been created that will ensure that this struggle continues without an effective government to deal with Egypt's galactic economic problems or to undertake necessary reforms. Egypt's voice will be loud, criticizing Israel and the U.S. and trying to broker Palestinian reconciliation, but its impact will be small.

Whatever the fate of Bashar Assad, Syria's capacity to project power on the regional stage has been dramatically reduced. The Assads — father and son — always played a weak hand well. Syria had power and influence — a strong military, a ruthlessness and skill in manipulating Lebanon, an emerging relationship with the West, even a disengagement with Israel on the Golan Heights, and a strategic bond with Iran. All of that was a function of a powerful regime. And now all of it is collapsing. Nobody knows what will happen, but the trend lines look increasingly like fragmentation of authority if not civil war. And for the foreseeable future, Syria's capacity to rule Lebanon, to seek the return of the Golan Heights and to throw its weight around the region is gone.

Unlike the Arabs, the "nons" have been rising for some time. With strong militaries, coherent political and economic systems and strong ties to one or more great powers, Iran, Israel and Turkey are effective actors. They each have a strong sense of national identity and purpose. More important, they are all stable countries, capable of asserting their power in defense of their own interests.

Israel has built a vibrant economy, a dominant military and maintains a strategic relationship with the United States. Iran has benefited enormously from the end of Saddam Hussein, the weakening of the Iraqi polity and the rise in oil prices. It has continued to pursue its aim of developing at least the capacity to produce a nuclear weapon. Turkey has managed — unlike any Arab state — to find a balance between Islam and modernity that allows it to be relatively democratic, competitive and highly relevant both in the Arab and Muslim worlds and in the West too.

All, of course, also function under serious constraints. Turkey's policy of maintaining close ties with every Arab/Muslim country has posed serious headaches as Iran and Syria have become international pariahs. Iran is not only a repressive state that faced serious internal opposition and could face more, but it is subject to potentially crippling sanctions from Europe and the United States. But what is so intriguing about the Iranians and the Israelis too is that even in the face of pressure, both have managed to maintain their own interests: Iran in resisting pressure to retard its nuclear program; Israel in its ability to maintain its security interests and to resist pressure to settle the Palestinian issue on any terms to which it's opposed.

The eclipse of the Arabs carries few positive consequences for the United States. Egypt will become a much less reliable partner as both its public and elites hammer America for its policies on Israel; Iraq will probably remain violent and unstable, certainly not a reliable buffer against Iranian ambitions; and Syria, an adversary that the U.S. at least knew, is evolving into a terra incognita, a potentially fractured polity in which regional powers and sectarian conflict will produce even greater instability. And in the interim, Iran's efforts to acquire a capacity to produce a nuclear weapon, and Israel's efforts to stop it, may drive the region closer to war.

Welcome to the new Middle East; it won't look anything like the old.