For centuries, Central Asia has been a battleground for outside powers such as the Persians and the Mongols or czarist Russia and the British Empire. The region, a major transit hub since the days of the Silk Road, became all the more appealing to foreign states after the discovery of significant oil, natural gas and mineral deposits there. In the quarter-century since the Soviet Union's collapse, Central Asia's security has become a paramount concern, attracting the attention of two neighboring giants, Russia and China. But although their spheres of influence overlap in the region, the story of Moscow and Beijing's engagement in Central Asia has so far been one of collaboration, rather than competition — at least where security is concerned.