A giant Thangka scroll painting, depicting a historical event witnessing Tibet as a part of China, was exhibited in Lanzhou, capital of northwest China's Gansu Province, June 18, 2012. [Photo/Chinanews.com]

A giant Thangka scroll painting, depicting a historical event witnessing Tibet to become a part of China, was exhibited in Lanzhou, capital of northwest China's Gansu Province, June 18, 2012. [Photo/Chinanews.com]

A 30-meter long giant Thangka scroll painting, depicting a historical event about Tibet becoming a part of China, was exhibited in Lanzhou, capital of northwest China's Gansu Province, on June 18, 2012.

The painting tells the story of the historical "Liangzhou Talk", an official talk between Kuo Duan, second son of Gedei Khan and grandson of the first emperor Genghis Khan in China's Yuan Dynasty (1271-1368), and Saban, 4th master of the Sakya school of Tibetan Buddhism and representative of Tibetan regional government in 1247.

After the talk, Tibet was officially included in China's territory and China realized its unity and harmony with multi-ethnic groups.

The ancient Liangzhou, today known as Weiwu City in Gansu Province, is famous for its distinctive tour resources and recoganized as the historical place witnessing Tibet to be united into China.