After Jericho, the Israelites conquered the city of Ai: they burnt it down and empaled its king.
(Joshua 8:1-29)

The name ‘Ai’ says it all. ‘Ai’ is the Hebrew word for ‘ruin’. And a ruin is exactly what Ai already was when the Israelites arrived: an abandoned ghost town that had been deserted for centuries.

In the 1930s, archaeologists discovered the ruins of a fairly big prehistoric city that was identified as Ai. But the place had been deserted for at least a thousand of years by the time the biblical invasion of Canaan took place.

Hence its name: ‘the ruin’. Apparently, the author of Joshua knew the place only as ‘the ruin’, because it had been a ruin for so long.

Excavations show that Ai must have been destroyed and abandoned around the year 2,100 BC. That’s the turbulent time when also Jericho was abandoned, as well as many other villages in the region.
It is impossible, however, that the Israelites are to blame: the conquest of Canaan by Joshua and his army is situated only many centuries later.

Ziony Zevit, "The Problem of Ai". In: Biblical Archaeology Review, Vol. XI (1985)

William Stiebing: "Out of the desert? Archaeology and the exodus" (1989)