Among the files, a key part of a research report on epidemic prevention by Japan's military medical academy was discovered by the Chinese researchers.
Xi, who is general secretary of the Communist Party of China Central Committee and head of the Party's military commission, was unanimously elected president of the People's Republic of China and chairman of the Central Military Commission of the PRC at the fifth meeting of the First Plenary Session of the 13th National People's Congress on Saturday.
"Hainan will further expand its connections with countries and regions participating in the Belt and Road Initiative to open itself further," Shen Xiaoming, governor of Hainan, said on Monday during a panel discussion at the four-day Boao Forum for Asia Annual Conference 2018, which closed on Wednesday.
Dr Awwad Alawwad, Minister of Culture and Information, said "The return of cinema to Saudi Arabia marks an important moment in the Kingdom's modern-day history and cultural life, as well as in the development of the Kingdom's entertainment industry."
Over the past five years, Hainan's GDP growth averaged 8.1 percent, reaching 446.25 billion yuan ($70.82 billion) in 2017.
Xi is a frequent guest to the Boao Forum for Asia annual conference, delivering speeches in 2010, 2013, 2015 and 2018. In the most recent address, he elaborated on opening-up and called for a shared future for mankind.