“put them to death and hanged them on five trees.” The hanging on the tree was a public declaration that the person had been cursed by God. As practiced by Israel, being hung on a tree was not torture because the person was already dead. Other cultures hung criminals up for public display (Gen. 40:19). The idea of crucifying a living person likely started with the Assyrians. The Assyrians “hung” people on stakes by impaling them when they were still alive, but generally they would have died very quickly. The Assyrians portray impaling in their bas-relief sculptures. Impaling was then used by the Babylonians and much more widely by the Persians. Alexander the Great (356-323 BC) brought it to the eastern Mediterranean countries, and the Phoenicians introduced it to Rome in the 3rd century BC. The Romans used crucifixion for torture, execution, and to cause public fear for 500 years until it was abolished by Constantine I in the 4th century AD.
“five trees.” The Hebrew word ets (#06086) has a couple of meanings and this could be “trees” or it could be five poles or upright stakes. It is similar to the Greek word xulon in that it could mean a tree or a stake.
“sunset.” Literally, “the going of the sun,” which is sunset. In this, Joshua fulfilled the Law (Deut. 21:22-23). Joshua’s action showed that these kings committed a sin worthy of death (cp. Gen. 15:16).