When late Cambodian king Norodom Sihanouk's late son Norodom Naradipo studied at Beijing No 25 Middle School, he was curious about how ancient Chinese referred to his motherland.

After Niu Chongyang, his history teacher, told him it was Zhen La (Khmer) in Mandarin, the boy felt more confused because zhen la can also mean "really spice" in Chinese.

This anecdote alongside dozens of less well-known stories will feature in an upcoming documentary series The Road to Friendship between China and Cambodia (Zhong Jian Youyi Zhi Lu), which will air on CCTV-4, one of China Central Television's Chinese international channels.

The five-episode documentary, which has been produced to mark the 60th anniversary of diplomatic relations between the two countries, recreates many historical moments from the 1950s through the 1990s.

Most of the content centers on Sihanouk, a key figure in Cambodian politics for more than six decades, and looks at his contributions, his friendships with Chinese leaders, as well as his life in exile in China.

Unlike most documentaries that employ a chronological order to narrate the stories, the production begins with the 1970s and moves to the 1950s in the second episode, with the third one about Sihanouk's friendship with former premier Zhou En'lai and the fourth about his return to China in 1979.

The year 1970 marked a turning point for Sihanouk, says director Li Yun, adding that during his visit to Moscow on March 18, 1970, then-Cambodian prime minister Lon Nol and his followers staged a coup to overthrow Sihanouk, causing Sihanouk to head to China.

"We obtained a video recording of his departure from an airport in Moscow for Beijing.

"In the past, Chinese TV programs have broadcast just a few minutes of this, but we got the original version which runs for more than 20 minutes," says Li.

To accurately portray history, the crew interviewed a number of people who were part of the story, including She Chunshu, a retired official who worked as a translator for Sihanouk for a long time, and Fu Xuezhang, the former Chinese ambassador to Cambodia.