After the 1921 British reconnaissance, attempts to climb Everest had been from Tibet because Nepal was closed to foreign climbers. Then, in 1950, Tibet's borders were closed when it was occupied by the People's Republic of China and by that time no expedition had been able to reach the summit. Partly on account of the political situation in Tibet, Nepal started allowing climbers entry in 1950 although it closed its frontiers again in 1966. During the period 1950-1966 three ridge routes were pioneered to reach the summit - the South Col—Southeast Ridge (1953), West Ridge—Hornbein Couloir (1963) and by a Chinese team via the North Col—North Ridge (1960). However, no summit attempt had been made on routes up any of Everest's faces. Nepal again allowed entry to climbers in 1969 and the Southwest Face, the only face accessible from Nepal, was such an attractive objective that Japan immediately mounted a spring reconnaissance in that year and returned in the autumn with a larger party with several climbers reaching on a line striking left from the central gully (black—cyan route on the diagram below).