Many early claims of world altitude records are muddied by incomplete surveying and lack of knowledge of local geography, which have led to reassessments of many of the heights which were originally claimed. In 1862 a khalasi (an Indian assistant of the GTS) climbed Shilla, a summit in Himachal Pradesh which was claimed to be over 7,000 m (23,000 ft) high. More recent surveys have, however, fixed its height at 6,111 m (20,049 ft). Three years later William Johnson of the GTS claimed to have climbed a 7,284 m (23,898 ft) peak during an illicit journey into China, but the mountain he climbed has since been measured at 6,710 m (22,014 ft).