Because the first was not known to surveyors. In the 19th century, the British conducted geodetic surveys in the Himalayas. They could not enter the territory of Nepal, which was then closed to foreigners, and took measurements from India from a distance of more than 200 km from the Nepalese peaks.
At that time, Kanchenjunga, on the border of Nepal and India, was considered the highest mountain. But in 1852, the Indian mathematician Radhanat Sikdar, based on measurements made by the British, calculated that the mountain, codenamed Peak XV, should be higher than Kanchenjunga. She needed to be given a name by which she would be recognized in the world. Not knowing the Tibetan name of the mountain (Chomolungma), the head of the British India Geodetic Survey, Andrew Waugh, named the peak in honor of his predecessor in this post, George Everest.
