True-to-life film shines a spotlight on the plight of China's 'left-behind' children, Cheng Yuezhu reports.

Director Bai Zhiqiang has long been capturing the essence of his home province Shaanxi, especially the northern regions known for being part of the Loess Plateau, the highlands in north-central China marked by yellowish soil and eroded mountains.

For years, he roamed the area and worked on documentary projects, but one fateful overnight stay at a rural primary school during one of his field trips proved to be a turning point.

In a conversation with the school's headmaster, Bai realized that almost all of the school's 160 students were "left-behind children", whose parents had left the nearby villages to find work in the cities. Some of them only had a single parent or were orphaned.