"Many people did not understand why I did this. They called me an idiot. They don't know the happiness I feel when I see the land turn green again," says Tubbat.

Carrying water is his greatest difficulty. They initially carried it themselves. They later used donkeys.

But more water was needed as they planted more trees. So, the couple then transformed a motorbike that can accommodate 48 barrels of water at a time.

Four years ago, Tosontsagaan had a stroke and couldn't continue planting trees. So, she stayed at home and did housework, giving Tubbat time to continue their dream of making the desert green again.

"My wife's support gives me energy," says Tubbat.

Tubbat was one of the first young people in his hometown to go to college in the 1970s. After graduation, he got a job with CCTV in Beijing.

But he chose to work with the local government to serve his hometown.

The couple has three children, who live in cities.

Their 38-year-old daughter initially refused to support Tubbat's decision.

But she changed her attitude after seeing her parents' happiness. She believes it's worthwhile.

Tubbat has also built a 10-km green fence in the desert to counter sandstorms.

"Our children want us to live in a city. But this is not the right time. I want to grow more trees," he says.

Tubbat is happy many locals have begun to plant trees after hearing his story.

Some have even visited him to learn how to plant saxaul in the desert.

"A tree is a water pump. It can bring rain and animals," he says.

"I want to be a tree, to grow up in the desert and block the sand until I die."