"The strange and scrappy underground world of Sanhe bears little resemblance to Shenzhen with which we have long been familiar. There's no shortage of residents who have lived in Longhua for years but have never heard of Sanhe. What's happening in Sanhe sounds like a tale of two cities," he added.

"A key chapter of the story is the wealth gap," he said. "Just a street away from Sanhe labor marketplace, you can find my residence, which is called Longteng Garden. It stands by a small patch of tile-roofed houses, and is an urban slum recognizable to almost every Longhua dweller at first sight. Two blocks away, there's a high-end residence called Jinxiu Yuyuan, located next to a swathe of 'handshake' buildings - concrete blocks in urban villages that are so close to one another that neighbors can virtually touch each other's hands from within."

Yang Wancheng, who runs the Shuangfeng Noodle Restaurant said: "There are plenty of decent young people coming here with dreams of landing plum jobs. But, the weak-minded fall prey to laziness and end up as so-called dashen."

He urged those who rely on his eatery for three cheap meals a day to seriously look for work. However, he probably won't see them make the change because a redevelopment plan is in place.

Vanke, one of China's largest real estate developers which is based in Shenzhen, plans to use the area as a testing ground for long-term rental apartments, with rents ranging from 2,000 to 4,000 yuan a month - well beyond the reach of most migrant workers.

Fading glory

As the area succumbs to modernity, it won't take long for the internet bars, cheap hotels and small stores that have made Sanhe a paradise for dirt-poor idlers to call it a day, according to Yang.

He sees Sanhe's fading from the scene as manifest destiny; an inevitable part of Shenzhen's ambition to build new, gleaming residential and commercial districts to reflect its stunning rise.

However, even in the midst of such unbridled development, consideration must be given to the plight of the migrant workers.

"During its heyday, the three-story offices of Sanhe Human Resources were a sea of people. But now, the bustle of recruitment can only be seen on the ground floor," said Liu Yong, a dashen who has lived in Sanhe for a long time.

Fielding Chen Shiyuan, an Asia economist at Bloomberg Intelligence in Hong Kong, said the ever-widening wealth gap is no excuse for people's choice of underemployment and even unemployment.

Despite that, the chasm between the vast virtual world depicted by the internet and smartphone, and the migrant workers' limited real-world choices are a real issue.