Midway through the ceremony, held in Dharamsala, the north Indian refuge for Tibetan exiles, the Dalai Lama paused and gestured nonchalantly toward the boy: “We have the reincarnation of Khalkha Jetsun Dhampa Rinpoché of Mongolia with us today.” This was, in the world of Tibetan Buddhism, a mic-drop moment. The last Jetsun Dhampa – one of the religion’s most important figures – died in 2012. But the significance of the announcement was not only religious. The Dalai Lama had managed to outmanoeuvre China in the geopolitical chess game of reincarnation.

Seven years ago, the Dalai Lama told a press conference in Mongolia that he was convinced Jetsun Dhampa’s reincarnation had been born in the country. “However, the boy is very young right now,” he said, “so there is no need for haste in making an announcement.” The Chinese government, which claims sole authority over all Tibetan Buddhist reincarnations, was incensed. It closed its main border crossing with Mongolia and delayed loan negotiations with the cash-strapped country.

Then there was silence. Under Chinese pressure, Mongolia, which along with Tibet is a centre of Tibetan Buddhism, banned the Dalai Lama from future visits. To stiffen the Mongolians’ resolve – and embolden the boy’s reluctant parents – the Dalai Lama sent in one of his most influential spiritual advisers: a monk named Thubten Ngodup. Thubten is the medium of the state oracle of Tibet, whose visions have guided the decisions of the Dalai Lama and his predecessors since the 16th century. He met in secret with the boy and his parents, offering reassurances and counselling patience. “The family was a little nervous, uncomfortable, but slowly, slowly, they came to accept their fate,” Thubten told me. “We still had to keep it secret because we didn’t want China coming up with their own fake Jetsun Dhampa.”

When the Dalai Lama introduced the boy in March, Tibetan Buddhists were thrilled at the audacity: not only had the Dalai Lama found the reincarnate lama beyond China’s grasp, he had managed to pull it off in secret. What’s more, the boy had been born in Florida, giving him the added protection of a passport from a government that has staunchly defended Tibet’s right to choose its spiritual leaders. With a single revelation, the Dalai Lama had created a possible template for an even more important reincarnation to come: his own.

Reincarnation might seem like an esoteric subject for 21st century geopolitics, especially for a secular state like the People’s Republic of China. But the Communist Party’s efforts to manage the transmigration of Buddhist souls are part of a contentious, decades-long campaign to absorb Tibet into China and control Tibetan Buddhism. In this existential contest, the reincarnations of the senior monks known as lamas have become a battleground for the future of Tibet. And no reincarnation is more consequential or volatile than that of the Dalai Lama himself.

At 88 years old, the Dalai Lama is frail enough that three monks assist him – one on each arm, one girding his waist – as he shuffles across the grounds of his monastery in Dharamsala. For more than six decades, ever since he escaped across the Himalayas from invading Chinese forces in 1959, the Dalai Lama has sustained and unified his people, elevating their struggle into a global cause. China claims sovereignty over Tibet, and insists that its forces liberated Tibetans from poverty and slavery. In response, the Dalai Lama has single-handedly spread a counter-narrative of his homeland as non-violent, noble and unjustly oppressed. It is almost impossible for Tibetans – and the world – to imagine a Tibet without him.

But the Dalai Lama is approaching his final years at a time when China has never seemed stronger – or Tibet more vulnerable. The 6m-7m Tibetans still inside Tibet live under increasingly harsh Chinese rule. Billions of dollars in Chinese investment have been accompanied by a systematic weakening of Tibetan religion and culture, along with tight restrictions on movement and communication. An estimated million Tibetan schoolchildren are now compelled to attend Chinese-language boarding schools away from their homes, raising fears that their own language will soon disappear. Meanwhile, the estimated 150,000 Tibetans in exile, scattered across the globe, are at risk of losing their identity and unity as another generation comes of age with no memory of their homeland. “Tibet is dying a slow death,” Penpa Tsering, the president of the government-in-exile in Dharamsala, told me. “China is slowly, slowly constricting us like a python.”

Many Tibetans have tethered their hopes to the Dalai Lama. He is the 14th human incarnation of the first Dalai Lama, who was born in 1391 and considered the reincarnation of one of the most enlightened beings in Tibetan Buddhism, Avalokitesvara, the bodhisattva of compassion. He has led his people through 15 American presidents and all 74 years of the People’s Republic. Through his reincarnated lineage, he connects Tibetans to the bedrock of their history.

But what will happen when the Dalai Lama leaves this world? As a spiritual adept who wishes to continue helping others achieve enlightenment, the Dalai Lama is believed by Tibetan Buddhists to have the ability to choose the body into which his soul transmigrates. The Chinese government, however, has other ideas. Tibetans are now bracing for the emergence of two Dalai Lamas – one chosen by China, the other by the Dalai Lama or Tibetans close to him. Faced with this bizarre scenario, the Dalai Lama has been playful and elusive about his intentions. He has suggested, at various times, that the next Dalai Lama could be a girl, an adult or nobody at all. He might opt for an “emanation” – choosing someone while he is still alive – rather than a “reincarnation” after his death. The only certainties the Dalai Lama offers are that his successor will be born in a “free” country – not Tibet – and that he alone has the power to decide. “This is a religious matter,” he says. “As far as my own rebirth is concerned, the final authority is myself…obviously, not Chinese Communists!”