A PLA official visits a zhiqing dormitory in the Heilongjiang Construction Regiment. [Photo provided to China Daily]

On Oct 10, more than 200 people in their 50s were at a lecture hall at the National Library of China, singing in chorus: "(We) enjoy the caress of spring together, and go through winds and rains together."

The group had gathered for the release of a Chinese book, Our Years in the Regiment, about the years they spent together in the Heilongjiang Construction Regiment more than 30 years ago.

On June 18, 1968, the Chinese government approved the establishment of the regiment for the exploration and construction of Beidahuang (which means big northern wasteland), a fertile region in Northeast China's Heilongjiang province.

During the Qing Dynasty (1644-1911), the Manchu government forbade the Han people from entering this region. The land was left uncultivated until the 1950s.

In 1968, about 345,000 zhiqing, or educated youth, were sent to live and work in Heilongjiang from cities like Beijing and Shanghai for the construction of Beidahuang.

They formed the largest zhiqing group of the total 17 million zhiqing sent to the countryside during the "cultural revolution" (1966-76).

These young people volunteered to serve the country, or were forced to abandon their studies in middle school or high school in comparatively more developed cities and leave their hometowns to work in the wastelands on China borders.