This week, just when China and India were making progress in easing weeks-long border tensions in Ladakh, the clashes between the two turned deadly for the first time in decades, leading to dozens of victims on both sides. Unfortunately, this tragic development is emblematic of the broader evolution of Sino-Indian ties and their gloomy future.

If the 21st century is to be the Asian century, this is thanks to China and India, the world’s most populous countries and, one day, its largest economies, as it has been throughout most of history. But, through the past millennia, China and India had few political ties or interactions. They were neither allies, nor enemies, each living in its own part of Asia, separated by Tibet, Indochina and Central Asia. This inevitability changed in the modern world system.

When the Republic of India and the People’s Republic of China were proclaimed after the Second World War, it was easy to hope that these two countries would lead the charge for decolonization and greater development of the Global South. The famous slogan of “Hindi Chini Bhai Bhai,” proclaiming that “Indians and Chinese are brothers,” was born in those years of hope.

But the dreams didn’t last long: Tibet, the very place that once separated China and India, ended up dividing them. The Sino-Indian War of 1962 wasn’t just a confirmation that geopolitics and nationalism would get in the way of cooperation between the world’s two most populous countries. It also left a deep mark on the Indian national psyche, which persists until today. While in China the war hasn’t received as much attention, its memory has shaped numerous generations in India, creating a reflexive wariness of China.

Over the subsequent decades, both countries continued to develop, while also deepening their economic ties. The border tensions subsided for a while and the two governments tried to negotiate a final agreement. After the turn of the new millennium, as China became the second largest economy in the world and the BRICS forum was born, it was understandable if hopes for a future of China-India cooperation came back to life. Together, they could reform the world order and international organizations, strengthen scientific cooperation and generate new economic opportunities, fight for the interests of the developing world and help the world’s poor. Had they been located on different continents, this might have happened.

But time and again, China and India proved that theirs is a destiny of competition and confrontation. From the heights of the Himalayas to the shores of the Indian Ocean, China and India just can’t get along. In the ten years since the Great Recession, which was thought to herald the end of US supremacy and the shift of economic power to the Asia-Pacific, confrontation, instead of cooperation, has become the norm: the skirmishes in Daulat Beg Oldi, Doklam and now in Galwan have deepened Sino-Indian tensions.

For the Western world, this conflict, far away in the heights of the Himalayas, might seem remote. But for the almost three billion people living in China and India, it is a pivotal event. Nationalist sentiments are running high in both countries, but the border tensions are leaving a deeper mark in India, where the threat of China looms larger. New generations of Indians, who could have grown looking up to China’s economic success and might have felt more removed from the legacy of 1962, have instead been left with their own wounds. Almost half of India’s population is under 25 years of age. Instead of growing up with images of Sino-Indian cooperation, they are seeing images of conflict, which they will take with them in position of political, economic and military power over the next half century.

While distrust of China has deepened, the areas of dissension have also expanded, reaching the Indian Ocean, where every Chinese move is being watched with suspicion by India. Two years ago, there were worries that an internal political dispute in the Maldives could lead to a military conflict between Beijing and New Delhi. So much for hopes of China-India cooperation in other countries. Sino-Indian competition will only continue to expand, from the Indian Ocean to the South China Sea, to Africa and, ultimately, to outer space, with both countries ramping up their space programs.

What will be lost in this future of China-India confrontation is not just the tangible benefits that their cooperation could have brought, not just in Asia, but throughout the world. It is the very ideas of a peaceful Asian century and friendly cooperation between the world’s developing countries for a better future for their people. In the end, geopolitics prevailed.

The irony is that it would have been in both countries’ strategic interest to settle the border disputes and maintain friendly relations. With India as a friendly partner, almost all of China’s land border, from north, to west, to south, would be safe, and the Chinese government would be free to focus on its eastern maritime expanse, with Korea and Vietnam creating the only terrestrial worries. On the other side of the Himalayas, Pakistan would be India’s only threat, with New Delhi no longer worrying about a more powerful country pressuring it not only along 3,000 kilometres of northern border, but also in the Indian Ocean.

While China’s rise is increasingly perceived as a threat, the Western World’s main focus is on US-China tensions. The China-India conflict is seen as a sideshow to this so-called “New Cold War”. The deadly border clashes have received nowhere near the attention similar US-China tensions would have received. But while they might seem distant events, for more than a third of the world’s population, the Sino-Indian rivalry is taking center stage. And their conflict is more likely to turn deadly than Sino-American tensions.

The border dispute might have been solvable sometime at the turn of the millennium, but it has become more and more difficult to see how an agreement could be reached, because of internal political pressures in both countries. War will hopefully be avoided, at least on the short term. Because of its non-aligned mindset in foreign policy, India will probably not explicitly join an anti-China coalition and the two countries will continue to see their economic ties intensify and to cooperate in certain areas.

But strategically, it should be clear that their destiny is one of confrontation and China and India will act accordingly. As they continue to develop and increase their power, the impact of their rivalry will become global. If the first half of the 21st century will be marked by a US-China “Cold War”, it’s likely that its second half will be shaped by a Sino-Indian one. And the world is watching how Hindi Chini Bhai Bhai is slowly turning into Hindi Chini Bye Bye.