Peruvian Band of Holes - photo

[Frank S]

If you ask me and fortunately most don't, I would say those holes were dug to form a barrier to slow or deter an evading force. An infantry or a Calvery would find negotiation the holes most distressing at best. many if not most of the holes were carved out of rock so originally the sides of them could have been near vertical. Even a shallow hole of a meter in diameter and half a meter deep would be crippling to a horse and an army would be slowed to neatly a standstill while attempting to march several 1000 soldiers through them