The 1921 British Mount Everest reconnaissance expedition set off to explore how it might be possible to get to the vicinity of Mount Everest, to reconnoitre possible routes for ascending the mountain, and - if possible - make the first ascent of the highest mountain in the world. At that time Nepal was closed to foreigners, so any approach had to be from the north, through Tibet. A feasible route was discovered from the east up the Kharta Glacier and then crossing the Lhakpa La pass north east of Everest. It was then necessary to descend to the East Rongbuk Glacier before climbing again to Everest's North Col. However, although the North Col was reached, it was not possible to climb further before the expedition had to withdraw.