A 9-year-old boy from Southern California has become the youngest person in recorded history to reach the summit of Argentina's Aconcagua mountain, which at 22,841 feet (6,962 meters) is the tallest peak in the Western and Southern hemispheres.

Tyler Armstrong of Yorba Linda reached the summit on Christmas day with his father Kevin and a Tibetan sherpa, Lhawang Dhondup.

Nicolas Garcia is handling expedition logistics from the city of Mendoza. He tells The Associated Press that when they reached base camp, Tyler was much less tired than his dad and their guide. Garcia says only one younger person is known to have climbed the mountain — an Inca boy who was sacrificed on one of the mountain's lower peaks in pre-Columbian times, and whose mummy was recovered in recent years.