Tenzing got Hillary up Everest in '53 and earlier had been very nearly to the top a few years earlier, with the Swiss. Tenzing's nephew, uncle (or something) Nawang Gombu got J. Whittaker to summit on first American Ev. exped. ten years later. Obviously, it wasn't just chance that sherpas, rather than the "white guys" (who were paying scads of $$ and calling the shots) were in those slots. So I'd say by the 1950s Sherpas were totally up to speed. The guiding "industry" as known today in the Himalayas probably began emerging in thye 1980s.

Tenzing got Hillary up Everest in '53 and earlier had been very nearly to the top a few years earlier, with the Swiss. Tenzing's nephew, uncle (or something) Nawang Gombu got J. Whittaker to summit on first American Ev. exped. ten years later. Obviously, it wasn't just chance that sherpas, rather than the rich foreigners, were in those slots. So I'd say by the 1950s Sherpas were totally up to speed. The guiding "industry" as known today in the Himalayas probably began emerging in thye 1980s.