Nowadays, China increasingly looks like a potential economic partner for not just Russia, but for Central Asian countries. China, as an energy-hungry country, will replace Western importers.
Also, importing energy resources from Central Asia and Russia is much safer than importing from the Middle East. In the past, pirate attacks on the oil tankers in the Strait of Malacca and the unstable political situation in the Middle East increased insecurity for China's supply of energy resources. Thus, China is looking for safe import from their energy-producing neighbors.
The latest events, especially a China-Russian $400 billion energy deal, where Russia will supply China with 38 billion cubic meters of gas annually for 30 years, are the important steps in this process.