A government-run website in China posted a photo Monday that showed Zuckerberg, Facebook's chief executive, giving a tour of his company's Silicon Valley office to China's cyberspace administrator.
It's unclear when the visit happened, but according to the Associated Press, Zuckerberg and Lu Wei chatted about Chinese President Xi Jingping's "The Governance of China" because a copy of it was sitting on the Facebook CEO's desk.
"I also bought this book for my coworkers," Zuckerberg said, according to the Chinese report. "I wanted them to learn about socialism with Chinese characteristics."
In October, Zuckerberg showed off his Mandarian skills on stage during a visit to Beijing.
Wei was reportedly spotted several times with a wide smile on his face during his visit to Facebook, among a group of Internet technology companies he has blasted in the past.
On Thursday, Zuckerberg plans to return to center stage to answer users' questions in his second town hall session in as many months.