Almost half a century ago, Li Yongzeng ("Li Snr"), now 80, was among tens of thousands of Chinese people who were working in Tanzania helping to build the 1,860-kilometer Tanzam Railway, or TAZARA, linking landlocked Zambia to the Tanzanian port of Dar es Salaam.

Now, his 25-year-old grandson Li Shangyi ("Li Jnr") works in Malawi on the program of "Access to Satellite TV for 10,000 African Villages", part of China's aid to Africa to build the information highway as announced by President Xi Jinping at the Forum on China-Africa Cooperation Johannesburg Summit in 2015.

When grandfather and the grandson talk about their experiences in Africa, both are proud that they are personally involved in the country's friendship with the African continent.

They are among millions of ordinary Chinese and Africans who have been working together to promote the friendship forged by the two peoples through their common historical experience and in their struggles for national independence and liberation.

In fact, since Egypt was the first African country to establish diplomatic ties with China in 1956, the past six decades have witnessed the traditional friendship between China and Africa flourish.

The Tanzam Railway built with Chinese assistance is one of the landmarks of the China-Africa traditional friendship.

"The four years that I worked with my colleagues to build the Tanzam Railway is an unforgettable period in my life," Li Snr said.

His home has photos that he took in Tanzania when he worked on the railroad.

Though the pictures, mostly black and white, and the pages of his work records have turned yellowish, he takes them out from time to time to recollect those days.

Under each photo attached to an old photo album are a few words in neat handwriting recording the place and the time that the photo was taken.

Looking at the "valuable assets" he treasured for more than 40 years, Li Snr seemed to revisit history.

At the call of the Chinese government, Li Snr and his 100-plus colleagues left their homes in Tianjin in December 1970 and boarded the Yaohua passenger liner from Guangzhou in South China's Guangdong province to Dar es Salaam in Tanzania.

"The 13 days and nights of traveling on the sea was a terrible time indeed," Li Snr recalled.

Due to sea sickness, he vomited frequently. However, when the long, tiring voyage finally ended in Dar es Salaam, he quickly dedicated himself to the work.

"At that time, we considered it as a sacred undertaking to assist the development of African countries of the Third World," Li Snr said. "Nobody would step back in the face of difficulties."