The battle for Mosul in northern Iraq has highlighted the numerous fault lines that make up the future of the Middle East. Shi’ite militias bound for Tal Afar and determined to cut off retreating Sunni Arab Islamic State fighters said their next deployment would be in Syria. The conflict has brought to light Turkey’s renewed interest in redressing 100-year-old grievances over being denied a role in Mosul. Kurds are seeking independence when the dust settles.As we survey the Middle East today, we see a region divided almost purely on sectarian lines: Iranian proxies against Saudi Arabia in Yemen; a multiyear disagreement over the election of a new Christian president of Lebanon that boils down to Shi’ite Hezbollah confronting a coalition of Sunni and Christian political parties; a five-year war in Syria that has demographically changed the country, driving almost 11 million mostly Sunni Arabs from their homes and bringing in Shi’ite militias from Lebanon to Afghanistan, sponsored by Iran, to prop up Bashar Assad.Nowhere is this more true than in Mosul. The city has become a key to the region. The neighboring autonomous Kurdish region, known as the Kurdistan Regional Government, and the Kurdish desire for independence are a hinge on which the region revolves today. In four trips to cover the war against Islamic State in the Kurdish region, I’ve seen up close how this small state-in-the-making of eight million people plays such a key role in what is to come. One hundred years ago, when the British and French came up with the then-secret Sykes-Picot Agreement to divide the Middle East into spheres of influence, they neglected the role of ethnicity and religious sectarianism in their plans. They neglected Shi’ite Muslims entirely. France would get what is now Syria and Lebanon and northern Iraq, the British would receive the rest of Iraq and what is now Jordan, with an understanding that British influence extended over Egypt, Saudi Arabia and what is now Israel and the Palestinian territories.By the time of the Paris Peace Conference and the Treaty of Sèvres in 1920 which dissolved the Ottoman Empire, many diplomats continued to be wedded primarily to the demands of Sunni Arab dignitaries with whom they had become acquainted during the Arab revolt.There were of course exceptions. Some outlined plans for an Alawite and Druse state in Syria, a Maronite-dominated Lebanon, a Jewish state in what was then Palestine, a Kurdish state in parts of Turkey, an Armenian state around Adana in Turkey and rights for Assyrian Christians.The fantasy of a series of ethnic ministates was frustrated by rising Turkish and Arab nationalism. With the exception of Israel, a Jewish state in an Arab and Muslim region, the Middle East became dominated by Arab nationalists and monarchists after independence, and it became divided along Cold War lines.All of these 20th-century constructs and assumptions are now entombed on the battlefields of northern Iraq and Syria. The US-supplied Iraqi Army tanks of the 9th Armored Division fly Shi’ite flags on them, and Iraqi Army trucks drive to the front with images of the imam Ali. Islamic State and other extremist groups like it, such as Jabhat Fateh al-Sham (the Al-Nusra Front) in Syria, fly the black flag of Sunni Arab jihadism. No one cares about Michel Aflaq and George Antonius anymore.Secular Arab nationalism is dead, except in the dusty offices of elderly grandees who talk about the old days of Marxist intellectuals who once held court in Baghdad, Cairo and Beirut.But the simplistic story of Shi’ites vs Sunnis, Turkmens vs Kurds, Arabs vs Persians is also a mirage. In October Egypt joined Russia in opposing a resolution by the French at the UN Security Council that called for an end to air strikes on Aleppo. Saudi Arabia was outraged, complaining that Egypt had not joined Sunni Arab countries in the vote. Turkey, which vehemently opposes Iranian-backed Shi’ite militias such as Hashd al-Shaabi in northern Iraq, also said in June that it wants to triple trade with the Islamic Republic. Turkey, which has enjoyed good relations with Hamas under Recep Tayyip Erdogan and his Islamic- leaning AKP, has patched up relations with Israel. Saudi Arabia and Israel have warmed their covert relations based on shared views of the Iranian nuclear threat and fears of a weakening of American power and influence in the region. The Kurds have political parties that span the spectrum from being closer to Turkey, to being closer to Iran and fighting a guerrilla war in Turkey. There are Sunni tribes, such as the Al-Jughayfa in Haditha and Shammar in Iraq and Syria, who loathe Islamic State and viscerally oppose jihadist extremism.This new Middle East of complex sectarian and ethnic struggles might have been predicted if policy-makers had listened to some of the local leaders.Suleiman Assad, the grandfather of Bashar, once wrote to French prime minister Léon Blum in 1936 urging him not to abolish an Alawite ministate that existed under the French mandate in Syria. “You might see that it is possible to secure the rights of the Alawite minority with provisions of a treaty, but we assure you that treaties have no value in the Islamic mentality in Syria. As such, we saw this previously in the treaty between England and Iraq which [did not] prevent Iraqis from massacring the Assyrians and Yazidi.” He claimed great danger was posed by being shoehorned into a Sunni-majority Syria.A commission of inquiry sent by the League of Nations to study whether Mosul should be included in Iraq or Turkey concluded that “it is probable that the majority of them [people in Mosul district] would have preferred to [be attached] to Turkey than to be attached to Iraq.” These seem like two unrelated issues but both were historically important in the creation of modern- day Iraq and Syria. Assad understood the threat to minority communities, yet in the end the brutal war today is deeply tied to the attempt by the Assad family to rule Syria as a minority. The decision to keep Mosul in Iraq set up the current dynamic of a Shi’ite-majority Iraq trying to reduce the political aspirations of Sunni Arabs in places like Mosul. Much bloodletting and extremism have been the result.What we see in this 100-year arch of history is that the borders laid down and the frameworks created between 1916 and 1936 set in stone things that many people in the Middle East did not accept. Those changes that did take place – giving Alexandretta province (Hatay) to Turkey, giving Mosul to Iraq, dissolving the Alawite state and denying Kurdish rights to self-determination – were completed, with sometimes dreadful consequences.The genocidal inclinations of Saddam Hussein and then Islamic State toward groups such as the Kurds and Yazidis, respectively, stem from deep historical processes.Today, as Mosul is liberated from the extremists, there is a beginning of a rearrangement of the Middle East. Borders are more porous, as Turkey has moved into Syria, as Syria and Lebanon exchange populations. Large bands of conflict link Shi’ite minorities in Afghanistan with Syria, or they link Saudi Arabia, Turkey and the Kurds. This has an impact on Israel as well. At no time in recent memory was the Israeli-Palestinian conflict of less interest to people in the region. Rania Khalek, an activist and writer, noted on Twitter on October 25: “I’m back in Lebanon for the 1st time n 9 years and struck by how few people care about Palestine and Israel. People are consumed by Syria and ISIS.”Israel has become more integrated into the Middle East. Its brand of ethnic nationalism, which may have seemed out of step for a generation when people sought post-ethnic concepts and socialism in the region, is more in line with the tectonic changes that revolve around ethnicity and religion. To that end, some Kurds look to Israel as a model for a successful independent future, just as other countries look to Israel as a “lesser evil” against other dangers, whether it be Islamic State or Iran.For Western powers this regional dynamic should be understood in the long term. The search for quick solutions, conferences and agreements has shown how hollow words can be.There may be no easy solution to the Israeli-Palestinian conflict, just as there is no solution to Mosul that will satisfy Kurds, Sunni Arabs, Turkey, Iran and Baghdad. There may be no simple solution to the deep problems in Syria, Lebanon and Yemen.Remaining wedded to national borders and nation-states that are collapsing, without acknowledging all of these changes, is a formula for missing the future of the new Middle East that is being drawn.