This picture was taken five years ago a conference/knees-up to celebrate twenty years of the faculty at Xi’an Jiaotong University. I’m pretty easy to spot in the front row, since I am the only white face present. I’d flown in to deliver a lecture about “The British Perspective on the Belt and Road”, which was something of an eye-opener for the audience, as I delved into the history of other nations’ outreach initiatives, and some of the likely unwelcome consequences. I predicted, accurately as it turned out, that Gwadar in Pakistan would prove to be one of the more obvious flashpoints, and that the Balochi independence movement would soon start targeting the Chinese. For saying so, I was reprimanded by an earnest Party member who didn’t think I should be rocking the boat.

The next day, I hang out with my friend Dr Qiao Zhilin, who has been racking his brains in search of a historical site in Xi’an that I had yet to see. We wander up to the city museum and then along to the Blue Dragon Temple, sited on a shoulder of land a couple of storeys above the surrounding terrain – Tang dynasty maps tend not to have contour lines, so the fact that medieval Chang-an was not as flat as a pancake often eludes scholars. The view from one of its halls would have rivalled that from the Great Goose Pagoda itself, and you would have seen the whole checkerboard of Chang-an stretching out to the north and west.

Zhilin is irritated that the view now looks like everything else. Climb the hundred or so steps to the gate, and all you can see is skyscrapers all around. The temple sat in ruins for centuries, until the place was mobbed by Japanese tourists in the 1980s. It turned out to be the place where Kukai, one of the most famous Buddhist missionaries in medieval Japan, had studied. He would return to Japan and establish the Shingon sect.

Never ones to look a gift horse in the mouth, the Chinese bodged the temple back together again, and in 1985 the people of Shikoku (Kukai’s birthplace) donated an entire forest of cherry trees, so it would look suitably Japanese every spring. Online information about the precise place where he studied is very confused. Wikipedia thinks that almost everything of any note in Buddhist history happened at the Ximing Temple, which I have never heard of, and seems to be a confused conflation of a bunch of institutions in the shadow of the Great Goose Pagoda. But Buddhist temple tourism is a fierce competition for the attention of tourists to go to a bunch of places that are all effectively the same, so the ability to say “Famous Monk Slept Here” is worth something, as is an entirely arbitrary forest of cherry trees, that only looks good for two weeks a year but is all any visitor seems to talk about.

The park is full of Chinese dicking around with badminton racquets and shuttlecocks, and a troupe of Uyghur dancers doing their hand-wavy dance thing. Nobody pays any attention to the museum in the inner temple area, although it fast becomes apparent why, as the guards have installed a loud alarm that beeps constantly if there is anyone inside. This helpfully tells them if anyone is on the premises, but makes it incredibly difficult to examine exhibits about enlightenment and harmony if you are actually there. It’s as if Westminster Abbey hired a clown with a bullhorn to stand next you and go HONK-HONK every time you looked at something.

We retreat to a sutra room near the back of the temple, where we are waylaid by a crazy-eyed security guard who wants to talk about Buddhism. Mr Yang has an odd aura about him that I remember all too well from the clientele at a religious bookshop where I once worked. He asks me “What sutras you have in England?” Diamond, I tell him. “Awesome,” he replies, “that’s my favourite sutra” and launches into a diatribe about how all religions are the same beneath the surface, and anything was okay except atheism, which was plainly a poison on the face of the Earth.

I think, I observe to Zhilin as we leave, that we’ve just met someone whose parents said he couldn’t be a Buddhist priest.

But he is just a security guard, protests Zhilin.

Is he, though? Is he?

Clinging by his fingertips to any reason not to be at the conference, Zhilin insists on accompanying me to the bullet train station, and pads after me all the way to the security gates.

“I really have nothing else to do!” he says, staying until I disappear up the escalators and he can no longer see me. At least, I assume he went home after that. Maybe he is still there.

I haven’t seen him since. Filming on the fifth season of Route Awakening did not take me to Xi’an. An invitation for a speaking gig in Japan lured me away in the autumn when I would have otherwise dropped by. And then there was a pandemic, and one thing led to another…. My six-year visiting professorship officially lapsed, since it is the sort of thing that is renewed in person at a conference banquet. The postgraduate faculty has moved twenty miles west, so not even the buildings are the same. And the people I knew have gone.

For five years, Xi’an was a huge feature of my life. The overnight plane became as commonplace as a bus. I got to see several intakes of students come and go — for many of them, my family being the first foreigners they had met. But the five years since means almost everybody has gone — the newly arrived bachelor’s students who sat in the front row of my lecture, would have graduated two years ago. If I turned up on their doorstep tomorrow, maybe only a couple of postgrads would even know who I was, and even then only vaguely. All those many dinners and outings and lectures and encounters are all lost, like tears in rain. Three different professors at that December 2017 banquet suggested I might like to be a visiting lecturer at their universities, too, but these things take time, and application, and will, and more than anything else, legwork. It took years to build the trust of the faculty at Xi’an, to prove that promises to return were not empty platitudes. Qiao Zhilin and I still wave at each other occasionally on social media, and tell each other that someday soon normality will be restored, but we can never really go back.

My son, who grew up surrounded by an adoring cloud of Chinese girls, has pre-teen schooling obligations that mean he can’t just wander away to China for three months anymore. His mother, who was the reason we went to Xi’an in the first place, is not my wife any more, and she is also struggling with the logistics of returning to a place that is no longer the same place, with people who are no longer the same people, and is now lacking a free spousal interpreter.

As of this week, I have been gone for as long as I was there. The last time I was in Xi’an, the deputy mayor offered to make me an honorary citizen of the city. The next time I go, I expect I will just be another tourist.

Jonathan Clements is the author of A Brief History of China and The Emperor’s Feast: A History of China in Twelve Meals.