The National Palace Museum in Taipei’s decision to lend a 1,200-year-old masterpiece of calligraphy to a Japanese museum has prompted an outcry on the other side of the Taiwan Strait.

The fragile Requiem to My Nephew, written during the Tang dynasty by Yan Zhenqing will be on display in the Tokyo National Museum from Wednesday until February 24.

The ink and paper document had been preserved in Chinese imperial courts for centuries until it was taken to Taiwan by the defeated Nationalist forces at the end of the civil war in 1949.

The piece was last shown to the public in 2011 in an exhibition in the Taipei Palace Museum.

The state-run mainland tabloid Global Times reported that it would not receive proper protection, such as a ban on the use of flash photography, when it goes on display in Japan.

However, the museum told the newspaper that the work would be protected by a glass case and denied that members of the public would be allowed to take any photographs.

In mainland China, paintings from the Yuan dynasty (1271- 1368) or earlier are banned from being exhibited overseas.

Yan, a Tang dynasty loyalist, is regarded as one of the greatest calligraphers in Chinese history, and composed the obituary note in honour of Yan Jiming, who was killed during the An Lushan rebellion in Hebei province in 756, along with his father – Yan Zhenqing’s cousin – and 30 other members of his family.

Legend has it that the younger Yan was taken as a hostage to force his father, the governor of Changshan, to surrender but was put to death when his father refused.

The family was not able to recover any of Yan Jiming’s remains until two years later – and only his skull and one foot were recovered.

In great grief and pain, Yan wrote how the nephew was born with exceptional virtue and grew to be the family pride.

The note, which is believed to a draft of a more formal eulogy, shows various corrections and crossings out, but is regarded as a great masterpiece of the Xingshu, or running script, style.

The news of the loan to Japan triggered an outcry on social media, with the tag “Requiem to My Nephew” being read 230 million times on Weibo, attracting 146,000 comments.

“The original Requiem to My Nephew is too precious to be allowed for exhibition outside the country. It embodies the unyielding spirit of the Yan’s family who lost their lives fighting rebellions,” wrote one Weibo user.

“It embodies the grief of an uncle who had to write an obituary of his nephew while looking at his skull. It had to be relocated during war but why would it be lent to Japan for free and without proper protection?”

“I felt so sad,” wrote another user. “Let’s unite Taiwan by force. I can’t take it any more.”

Despite the popular outcry, the arts world appeared less certain that the loan was unjustified.

Ling Lizhong, curator of the department of painting and calligraphy at Shanghai Museum, said it was “normal cultural exchange”.

Ling told “The Tokyo National Museum has been putting on special exhibitions of ancient Chinese calligraphy, which shows respect and love for the Chinese culture.

“It is very common for museums to borrow exhibits. I hope one day the piece will be exhibited in the Shanghai Museum.”

Shanghai Museum is currently running a special exhibition dedicated to the Ming dynasty calligrapher Dong Qichang, which includes a work by Yan Zhenqing that was borrowed from a museum in Tokyo.

In 2010 it exhibited works from the Tang, Song and Yuan dynasties that included 39 pieces borrowed from Japanese museum.

The Guangming Daily, one of the heavyweight party mouthpieces, carried a commentary by Zhou Juanxia from the Chinese Academy of Social Sciences that argued that the work being lent by the museum in Taipei was an indispensable part of China’s cultural heritage and would need extremely careful handling.

“The piece is more than 1,200 years old and it is at the end of its time in human life. We can understand the fragility of the paper and the public’s anger,” Zhou wrote.

“The practice of the National Palace Museum in Taipei is not a blessing for cultural relics. I hope the museum can put aside other factors and carefully consider loaning cultural relics.

“I also hope that the seal at the end of the manuscript urging ‘future generations to safeguard this’ can be promise kept by generation after generation.”