Sun, 31 Mar 2019
This is the “rook” that is a sort of crow, C. frugilegus. It is not related to the rooks in chess. That word is from Arabic (and earlier, Persian) rukh, which means a chariot. Before the game came to Europe, the rooks were chariots. Europeans didn't use chariots, so when they adopted the game, they changed the chariots to castles. (Similarly the elephants turned into bishops.)
Okay, I've known all this for years, but today I had another thought. Why were there chariots in the Persian form of the game? The Persians didn't use chariots either. Chariots had been obsolete since the end of the Bronze Age, thousands of years, and chess is nothing like that old.
The earliest forerunner of chess was played in India. But I confirmed with Wikipedia that it didn't overlap with chariots:
Were the Guptas still using chariots in the 6th century? (And if so, why?) I think they weren't, but I'm not sure. Were the chariots intentionally anachronistic, even at the time the game was invented, recalling a time of ancient heroes?
[ Addendum 20200204: Consider the way modern video games, recalling a time of ancient heroes, often involve sword fighting or archery. ]