Organised violence – the term war boils down to – has long been a unifier of peoples. Archeological evidence shows that nearly half those who lived during the last part of the Stone Age in Nubia, an area along the southern reaches of the Nile River, died violent deaths. Many other tribal societies through the ages have shared this mortality pattern, which suggests large-scale mobilisation for killing rather than widespread random violence. Orchestrating raids on neighbouring Nubian settlements took coordination among villagers, as did fending them off. Attackers and defenders alike had to marshal resources, make plans and build trust among one another in order to fight effectively. Cooperation, mutual dependence, trust – even in killing others – are building blocks of political order, the foundational elements of states.

The advent of agriculture was a prerequisite to long-term human settlements – cities – of any significant size. It gave rise to larger societies, capable of bigger and more elaborate wars. For the dynasties of ancient China, the empires of Mesopotamia and, centuries later, the kingdoms of Europe, waging war was one of their reasons for being. Frederick William founded and built Prussia to wage war against its many hostile neighbours. Prussia’s clashes with regional rivals during the 17th and 18th centuries made the nation we know today as Germany. Across the Atlantic, in the mid-18th century, the Seven Years’ War helped to galvanise American colonists against the British, setting them on the path to form a nation of their own.

Across this long history from the Stone Age to the modern era, the basic political formula remained the same. Disparate elements of a society learned to cooperate outside familial structures in order to arm themselves for plunder, defence – or both. They formed hierarchies, bureaucracies and institutions that endured and evolved. For emerging nations, the aftermath of the wars imparted important shared experiences too. Defeat could be even more unifying than victory.

The last major nation-building war came in 1980, when Iraq under Saddam Hussein attacked Iran following the Iranian Revolution. When Hussein launched a ferocious assault reminiscent of fighting from the First World War, Iran was woefully unprepared. The Iranian revolutionaries drew on religious commitments to help galvanise legions of fighters. Iranian men young and old flung themselves against Iraqi tank attacks, again and again, until Iraq’s advance ground to a halt. For Iran, it is difficult to overstate the legitimacy this achievement gave the new regime, and the cohesion the war imparted to Iran. Iranian society cohered around grief, fear and a renewed sense of Persian identity in response to Arab invaders, both Sunni and Shiite.

Since the Iran-Iraq War (1980-88), wars have tended to be mainly destructive forces for nations. Countries amid the throes of war now seem to be breaking down rather than rising up. In countries today ranging from Libya to Myanmar, conflict is undermining governments, and threatening to undo nations much as strife tore apart the former Yugoslavia in the 1990s. In Iraq, a war initially launched 14 years ago by the United States to save the country has gone on and on, and become a source of the nation’s internal decay. Meanwhile, South Sudan, the world’s newest nation, is in a downward spiral of internal violence. The country won its independence from Sudan after more than two decades of fighting. Patterns in history suggest that South Sudan should have emerged from that ordeal unified despite the many challenges the country faced as a young nation. Instead, it essentially collapsed amid infighting upon independence, launching yet another war that has displaced more than 2 million of its 12.5 million people.

The experience of South Sudan is the new norm. Armed conflict, whatever its origins and outcomes, tends to be a scarring interruption to the progress of societies, setting back development and darkening prospects. Indeed, war has become a mortal ailment in modern states. The widely used terms ‘war-torn nation’ and ‘cycle of violence’ to describe conflict countries express the obvious fact that countries at war are countries in perilous decline. War seems to be the bleak end, not the beginning, for strong nations.

Part of the reason that war no longer helps to build nations is simply that few new nations are waiting to be built. Decolonisation and the end of the Cold War brought scores of new countries around the world into being. In addition, the prospect of a country waging a war of conquest and subsuming or incorporating a neighbour violates norms of international politics established in the late 20th century. What nations there are remain, for the most part, within their borders. Many of the gains that used to require territorial conquest can now be achieved through capturing market shares, election rigging and military hegemony.

In the past, nation-building often involved appeals by political leaders to ethnicity and ideology. But the ethnically driven politics and violence that many nations embraced in their early history have fallen into disrepute, and would likely draw accusations of war crimes. Perhaps more importantly, no forceful ideas animate global politics as they once did. At the end of the Second World War, Sukarno, the leader of modern Indonesia, promoted an ideology of his own making that mixed nationalism, Marxism and Islam as part of his successful effort to unify Indonesia. For Sukarno, the major beliefs and ideas coursing through the world at the time provided a means to build a vast and populous nation from an ethnically diverse chain of far-flung islands. But global politics today is bereft of big ideas and revolutionary ideologies. Most nations have conformed to the Washington Consensus on norms in governance and economics. Even the remaining autocracies largely play by those rules. Only a few countries in Latin America – Bolivia for example – boast political movements at the national level aimed at any meaningful challenge to neoliberalism.

In sum, the age of nation-building might be over. Let’s hope so. Nation-building involves, at bottom, the violence of internal repression and external conflict. Revolutionary-era France, Jacksonian America and Maoist China – three signature periods of nation-building in global history – are as notorious for their crimes as for their enduring accomplishments. While the end of the age of nation-building might be a boon to the world generally, it is little comfort to countries struggling to establish themselves. There will likely be no Sukarno for Afghanistan or Somalia, two countries where a series of aspirants have failed for decades to become truly national leaders, or to strengthen their countries’ nationality. Iraqi Kurdistan, the Kurdish territory of Iraq, a nation without a state, is unlikely to raise its own flag any time soon, remaining in a kind of semi-autonomous status. This is the source of enormous frustration to Kurds of the Middle East, as the recent referendum on independence in Iraqi Kurdistan clearly showed. But the path to nation that many Kurds seek seems to have vanished.