Young African traders who want to follow in the footsteps of Dieng's generation complain of difficulties getting visas, police crackdowns and prejudice, which come amid rising nationalism and slowing economic growth.
Guangzhou is believed to have the largest African population in Asia, but many are leaving as long-time traders struggle against a slowdown in the Chinese economy and increased competition from Chinese traders and the internet.
"They come with their bags, they sit down, they don't have anywhere to sleep, they don't have money," said the father-of-four. "Most of them, after 10, 15 days they go back."
Over recent decades, Chinese companies and entrepreneurs have spread out across Africa building stadiums, roads and other large projects, cultivating land, running hotels and opening restaurants. Less well-known are the thousands of Africans who live in or regularly visit the southern trading port of Guangzhou, which neighbours Hong Kong.
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The first African traders started arriving in Guangzhou in the late 1990s, attracted by its annual international trade fair, China's economic boom and the ease of doing commerce in the city thanks to its wholesale markets, factories and low prices.
Guangzhou had benefited from being one of the first Chinese cities allowed to open up to business in the 1980s, giving it a head start in attracting exporters.