Ajalon (also spelled Aijalon or Ayalon; Hebrew: אַיָּלוֹן or איילון) was a place in the lowland of Shephelah in the ancient Land of Israel, identified in the 1800s as Yalo at the foot of the Bethoron pass, a Palestinian Arab village located 13 kilometres (8.1 mi) southeast of Ramla in the West Bank but destroyed in 1967.
The place may have been the site of several battles between invaders and the natives. In the Tell el-Amarna letters, written during the last twelve years of Pharaoh Akhenaten and the first regnal year of Tutankhamun (14th century BCE), Abdi-Heba spoke of the destruction of the "city of Ajalon" by the invaders, and describes himself as "afflicted, greatly afflicted" by the calamities that had come on the land, urging the king of Egypt to hasten to his help.
Ajalon is mentioned in the accounts of an invasion of Palestine by the Egyptian king Sheshonk I of Egypt in the 10th century BCE.
This event may have been connected to an attack of the Amorites, before the arrival of the Israelites under Joshua. But since the valley stretches as far to the west as to a point halfway between Sha'alvim and Latrun, the city referenced in these letters may have been any settlement in the valley.
The Valley of Ajalon was first mentioned in the Book of Joshua as where Joshua defeated five Amorite kings. Following his midnight march to rescue the city of Gibeon from the coalition led by the King of Jebus (Jerusalem), Joshua pursued the coalition eastward, down through the descent of Beth-horon, and then southward across the Valley of Ajalon. To allow the Israelites to complete the rout before nightfall, Joshua asked the Lord to lengthen the day by uttering the command: "Sun, stand thou still on Gibeon; and thou, Moon, in the valley of Aijalon". Joshua 10:11-14 records that the sun cooperated with Joshua's request.