Aaron was 123 when he died on Mount Hor.
Moses was eighty and Aaron was eighty-three when they went and spoke to Pharaoh.
Aaron the priest climbed Mount Hor as the Lord had directed, and he died there on the first day of the fifth month, in the fortieth year after the Israelites had left Egypt.
(The Canaanite king of Arad, who lived in the Negev in the country of Canaan, found out that the Israelites were on their way.)