A total of 89 boys are participating in the ceremony, which runs from April 21 to 25.
"We made the effort for the festival, which costs a lot of money and takes a lot of time. But it's worth it as it helps families and members of the community stay close," said Saokham Muliew, a 48-year-old Shan villager.
"Without this Buddhist ritual, our culture will disappear," she said.
The temple in the village was built in the Shan architectural style.
In Poy Sarng Long ceremonies, boys are prepared for ordination as novices, then live in the temple for a few weeks.
Their families throw a lavish feast as part of merit-making. Each family spends about 50,000 baht on the event.
In the lead-up to the festival, villagers help each other prepare food and decorate makeshift tents where their sons will stay for five days before moving to living quarters in the temple.
By tradition, the boys do not walk during the ceremony. Adults take turns carrying the Sarng Long boys on their shoulders and taking them everywhere, including to the toilet. For the boys, it is a time they can ask for things like sweets and toys, the symbols of earthly pleasure that their parents usually deny them.
Pairoj Inta, or Nit, who is eight years old, said he had planned to ask for toys and sweets when he became a Sarng Long. But with his heavy costume, constantly running make-up and the scorching summer sun, Nit forgot his wish-list.
"I only asked for a fan because it is so hot," he said. Despite being tired, Nit said he was happy. "My family, too, is very happy," said the boy, smiling.
Characterised by vivid costumes, the festival is inspired by the story of Prince Siddhartha, who later became the Lord Buddha. The prince gave up the palace, his wife and son, for a life of austerity when he was 29, before enlightenment.
In Piang Luang, Shan people try to keep their cultural identity alive by various means, including Shan language classes in villages, said Mo-ngernhorm Kamphang, 42, a Shan who fled Burma's military suppression to Thailand two decades ago.
Nuntavatra Jongkham, a 24-year-old teacher, said the festival is now becoming a major event, drawing tourists.
He said it also reflects the fact that Buddhism is solid in the community. Around 90% of the people are devout Buddhists. During the opening of the festival, organisers were instructed to be careful to avoid giving the impression that Buddhism is superior to other faiths.
"Religion is a sensitive issue," he said.
"The Chinese, Karen and other tribes like the Muser and Lisu have different religious faiths, including Christianity. So we must respect them, even though they make up only 10% of the residents," said Mr Nuntavatra.