This period also saw some contacts with Jesuits and Capuchins from Europe, and in 1774 a Scottish nobleman, George Bogle, came to Shigatse to investigate prospects of trade for the British East India Company. However, in the 19th century the situation of foreigners in Tibet grew more tenuous. The British Empire was encroaching from northern India into the Himalayas, the Emirate of Afghanistan and the Russian Empire were expanding into Central Asia and each power became suspicious of the others' intentions in Tibet.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): When did the British and Russian empires begin encroaching on Tibet?
19th century