ULAN BATOR, Jan. 9 (Xinhua) -- A photo exhibition featuring the known and unknown aspects of the China-Mongolia friendship was held here Tuesday to commemorate the 70th anniversary of diplomatic relations between the two countries.

The exhibition, titled "what we know and do not know about the China-Mongolia friendship," showcased China's great efforts to promote bilateral ties and support Mongolia's economic and social development since the establishment of diplomatic ties.

"I am confident that the album can provide Mongolian readers with a deep understanding of China's outstanding contribution to the development and construction of Mongolia," said Khorloo Baatarkhuu, a leading Mongolian sinologist and editor of the album.

A total of 500 photos were exhibited, including many rare archive photos on China-backed infrastructure projects.

Senior Mongolian and Chinese officials, including Mongolian Deputy Prime Minister Ulziisaikhan Enkhtuvshin and Chinese Ambassador to Mongolia Xing Haiming attended the exhibition.

In his speech, Enkhtuvshin said that since the establishment of diplomatic ties 70 years ago, Mongolia-China relations have made great progress, which is inseparable from the selfless efforts of the Chinese government and the Chinese people.

For his part, Xing said that since China-Mongolia relations entered a comprehensive strategic partnership, high-level exchanges between the two sides have been frequent and political mutual trust has deepened. Meanwhile, economic cooperation and cultural exchanges have become closer, bringing tangible benefits to the two peoples.

Mongolia and China established diplomatic relations on Oct. 16, 1949. In the 1950s and 1960s, China sent large numbers of workers to Mongolia to help with its infrastructure development. Some of the projects have since become symbols of Mongolia-China friendship.