Given the frequency of relatively minor asteroidal impacts, similar to the Tunguska event, it seems to me that ancient literature would be rife with stories of them, probably interpreted as acts of the gods or God. For example, in the Bible is the story (2Samuel 24 and 1Chronicles 21) of David taking a census of the people, which angered God so much that he sent a pestilence that killed numerous Israelites: 1Chronicles 21:16 "And David lifted up his eyes, and saw the angel of the LORD stand between the earth and the heaven, having a drawn sword in his hand stretched out over Jerusalem." I don't know why pestilence would be associated with an impact, though. Having seen an artist's rendering of what the Tunguska event may have looked like, I can well imagine David having seen something similar. The sword the angel held could've been the trail left by an infalling bit of space depris, and the body of the angel could've been the explosion itself. Whether or not that specific case is an example of an impact in ancient literature (it may well not be), has anyone done a study of ancient mythology with the purpose of uncovering those kinds of events? Only a fairly small number would have occurred in regions we've got records of, but there should be many records of such awesome events.