I haven't contributed much to this subreddit because I'm way out of my depth. I compulsively read the threads though.
The latest episode of Hardcore History has gotten me interested in the Persians. I didn't want to ask a redundant question, so I checked the FAQ and I couldn't find much of anything there. I also searched the subreddit for Cyrus, and, although there are a few posts, the subject matter does seem to be lacking here.
Anyway, based on my extremely limited knowledge, Cyrus, who founded the Persian empire, was only a few generations older than Alexander the Great, who effectively ended it. Is this truly the case?
Cyrus the Great founded the Persian empire in the mid-6th century BC. Alexander lived in the late-4th century BC, over two centuries later. You may be getting Cyrus the Great mixed up with Cyrus the Younger, son of king Darius II, who launched an unsuccessful rebellion against his father in 401, resulting in his death at the battle of Cunaxa (as narrated in Xenophon's Anabasis).