Facebook’s own apps may be banned in China, but the company has a powerful tool to forge closer ties with large Chinese app publishers: its mobile ad network.

Apps such as China’s Baidu, Cheetah Mobile and APUS have quietly joined the largest sellers in Facebook’s network. Those apps—which range from mobile games like Piano Tiles to tools that help save battery life—are using the network to make money outside China.

Facebook’s systems help match Chinese apps to global advertisers that can choose to run their ads outside Facebook’s own apps. Typically, apps selling through the ad network get 70% of the revenue and Facebook gets 30%.  

And they say it is making meaningful money for them.