Li Wenshu, a businessman in Kashgar, remembers clearly how he was nearly suffocated by sand and dirt aboard the train when it started operating in 2011.

"You left an outline of a human body on the sleeper when you got up after the sandy sections of the railway line," Li said.

It was normal to experience sand and dirt when people traveled by train in the old days. Sometimes even the water tasted funny when the wind was strong.

In recent years, Xinjiang's railway department has improved the train cars and rails, including installing water purifiers on electric stoves and adding strips to the gaps between doors and windows to prevent sand from entering the cars.

"Before 2017, passengers had to taste sand and dirt," said Chou Hong, chief of the Urumqi depot dispatch section. "Now they have access to purified water and warm water, too, if they want it."

Borathan said, "The slow train impresses many people not only because of its low prices, but because it serves as a melting pot where people of different ethnic groups can communicate."

In addition, he said, "On the train, we are free to sell products and dance if we are happy."