Every September, a small province in Thailand's lower north holds a festival for a banana. There are parade floats armoured in bananas, banana-eating contests, judging of the year's finest bunches, and the crowning of a Daughter of the Egg Banana, the fair's own beauty queen. It would be easy to file all this as agricultural marketing, and in part it is exactly that. But the festival's full name gives the game away: Sart Thai Kluai Khai, the Sart Thai Egg Banana fair. The banana is the headline act. Sart Thai, the day underneath it, is one of the oldest rites in Asia: the day the living feed the dead.

The Day of the Ancestors

Sart Thai falls on the new moon that ends the tenth lunar month, usually in late September. The name is older than Thailand: sart comes from the Sanskrit śrāddha, the Hindu rite of making offerings to one's ancestors, and the timing still matches. The same weeks that Hindu India sets aside for feeding its forefathers, central Thailand marks its own day for the dead. Families rise early, take food to the temple, and offer it to the monks; the merit of the gift is then dedicated onward, to parents and grandparents gone ahead, and to the hungry ghosts who have no one to feed them. The South holds its version as the Sat Duan Sip festival, and Isan as Boon Khao Pradap Din, when parcels of food are laid on the ground at temple boundaries for the spirits to find. The details differ; the transaction is the same. Once a year, at the turn of the harvest, the dead are owed a meal, and the living pay.

The rite has its own dish. Krayasart, a dense, chewy brittle of roasted rice, peanuts, sesame and palm sugar, is made in great pans for this one occasion, stirred by neighbours in shifts because the mixture fights back. Its name carries the rite inside it: the sweet of sart, cooked for the ancestors and given to the monks on their behalf. And krayasart comes with an instruction. It is rich, sticky and relentlessly sweet, and the traditional answer to it is a small banana eaten alongside: the kluai khai, the egg banana, short, round and delicate, whose harvest peaks in exactly these weeks.

"Once a year, at the turn of the harvest, the dead are owed a meal, and the living pay."

The Province and the Fruit

This is where Kamphaeng Phet enters. The province grows the finest kluai khai in Thailand; the city's nickname is Mueang Kluai Khai, Egg Banana Town, and the provincial motto lists the sweet banana among its official glories. So when the province built a great annual fair, it built it on the one day of the year when the whole country reaches for its crop. The Sart Thai Kluai Khai festival runs for around ten days each September at the Bodhi Tree Square by the provincial hall: the banana floats, the finest-bunch competitions, the krayasart stirred in public in vast woks, the light-and-sound show, and the Thida Kluai Khai pageant. At its heart, on the day itself, the older ceremony continues: monks receive alms at dawn, krayasart and bananas among the offerings, merit dedicated to the ancestors as it has been for centuries.

To be clear about what this is: a modern provincial fair, created to promote a cash crop, in a country where every province is issued a motto and a signature product. The machinery of promotion is entirely on show, and no one in Kamphaeng Phet pretends otherwise. Yet this is also what makes the festival honest. The pairing it celebrates is real; the harvest timing is real; the rite at its centre is still performed, not re-enacted. Most invented festivals borrow an ancient costume. This one wrapped a fair around a living ceremony and let the two feed each other: the ancestors bring the occasion, the banana brings the crowds.

The Diamond Wall

The setting deserves more attention than festival-goers usually give it. Kamphaeng Phet means "diamond wall", phet descends from the Sanskrit vajra, and the name refers to the city's ancient defences, because this was a walled royal city of the Sukhothai kingdom, known then as Chakangrao, guarding the route between Sukhothai and Ayutthaya. Its ruins are inscribed on the UNESCO World Heritage list together with Sukhothai and Si Satchanalai, and they are among the least visited great monuments in the country. In the forest section north of the walls, the aranyik temples of the forest monks stand in real woodland: laterite Buddhas dissolving into trees, and at Wat Chang Rop a great stupa held up by a ring of half-emerged elephants. A city of this rank, best known nationally for a banana, is a very Thai kind of understatement. Come for the fair, and give the ruins a morning.

When and How

The fair runs for roughly ten days each September, anchored to Sart Thai on the new moon ending the tenth lunar month; the dates shift with the lunar calendar, so check the year's announcement before travelling. Kamphaeng Phet is about five hours from Bangkok by car or bus, up the Ping River valley, and pairs naturally with Sukhothai an hour further north. Buy krayasart from the pans, eat it the correct way with a kluai khai in the other hand, and if you are at a temple at dawn on the day itself, you can watch the fair's ancient engine running quietly beneath the bunting: food passed to monks, merit passed onward, the year's debt to the ancestors paid in rice, sugar and small sweet bananas. Why Thailand's calendar keeps a day for the dead is a story our audio guides tell in full — coming soon in the Siam Curated app.