China signed a deal with Russia on Wednesday to buy natural gas for the next 30 years.
The value of the deal is $400 billion.
Russian gas is set to begin arriving in China as early as 2018.
Price negotiations continued into the final hours of a two-day visit by Putin to China, during which both sides had said they hoped to sign an agreement.
The gas deal gives Moscow breathing room during a time when both Washington and the EU have imposed visa bans and asset freezes on dozens of Russian officials over action taken in the Ukraine.
It also allows Russia to diversify its markets for gas, where it was previously focused on Europe.
The agreement “opened the door for Russia to enter into Asia’s gas market,” said Keun-Wook Paik, senior research fellow at the Oxford Institute for Energy Studies.