The Younghusband Expedition (1903-1904)

"The British under direction of Viceroy Lord George Curzon launched the Younghusband expedition in 1903 under the strong perception that Russia had been meddling in Tibet in order to gain dominance in the region as a means to use Tibet as a gateway to threaten Britain’s imperial colony of India. Although this perception proved false in the end, the decision and judgement was built up primarily out of the Viceroy’s own suspicions and experiences with Russia’s Asiatic policies. Through the expedition Curzon also sought to establish a definitive northern border with Tibet so that British India could properly fortify its frontier and to make sure that the agreed borders would be respected. Free trade between Tibet and British India was also sought to be opened through the expedition which would seek the opening of the Chumbi route to Lhasa. Lastly, the expedition was spurred out of European curiosities for the Tibet region that had been shrouded in mystery due to the isolationist policies imposed by both Tibet and its Chinese suzerain. "

http://tibettalk.wordpress.com/2008/12/18/the-younghusband-expedition/