From then on, whenever they spotted some unfamiliar plants, they would take photos and look them up online. Over 100 days of company had endeared the couple and their horses to each other. "We didn't have to tie them to a tree. They would stay around us."

It took them more than three months in Xinjiang, before they passed through Gansu province, Ningxia Hui autonomous region, and Shaanxi, Hubei and Jiangxi provinces on their way back to Quanzhou.

The couple removed the wagon and rode the horses after they got to Lanzhou, Gansu. They turned heads on the horseback in city streets. Children pursued them out of curiosity, asking them where they were going.

Zheng and Qing spent most nights in their tent. They lost a lot of weight on the way.

"We were often weather-beaten and couldn't get a shower," he says.

Overall, the 6,500-kilometer journey from Xinjiang to Fujian took them 18 months.

An online follower of Zheng's, who calls himself Panda, says Zheng's experience reminds him of his original aspiration of being adventurous and exploring the world.

"Maybe I don't have the courage at the moment, but I will, like he did," the follower writes after watching Zheng's videos of the trip on social media Toutiao.