Pictures in the book, Chinese Tea, feature a tea garden on Hainan Island and a woman picking tea leaves in Ya'an, Sichuan province. [Photo provided to China Daily]

"The planning and shooting of the documentary took two years, and we had collected a large amount of material about Chinese tea," says Liu. "But the information included in the documentary is limited by its format, so I wanted to present this information in the form of a book."

Liu started researching and planning the series in 2016, and had visited more than 10 provinces in China. The crew also shot sequences in Britain, Japan and Kenya.

"Chinese tea is actually an international cultural symbol, so we chose some countries that have been greatly influenced by Chinese tea," says Liu.

Graduating from Peking University in 1991, Liu later worked for China Central Television and Xinhua News Agency. He realized that there were not many Chinese documentaries about tea. Most instead focus on China's culture and customs.

"I think because there are too many aspects of knowledge about tea, it's complicated to explain everything," Liu says. He then decided to tell his audience about high-quality tea in season one－What is high-quality tea? Where is it made, and how did it make its way around the world?

Unlike food documentaries that show a variety of ingredients, locations and cooking skills, making an engaging series about tea proved more difficult－especially since the tea plants and tea making processes in different areas often appeared the same.

"Aerial footage of different tea gardens tended to look pretty similar, which sometimes even confused our editors. So we only chose footage that added a visual impact to the stories we were telling in the documentary instead of relying on them to show the full picture," Liu says.

"The limitations of the documentary format were made up for in the book. Since the book follows the same logical lines as the series, we were able to include much more background information in the publication."