I know in ancient warfare slings were used and some people were know for being particularly effective with them. but I could seem to find info on how long they were used for or when they stopped using regiments of slingers in any fashion.
You don't seem to have gotten any good answers yet, so I'd like to point you to a number of previous conversations in this subreddit about this (or similar) topics:
Why did the sling fall out of favor as a weapon of war?
When were slings no longer used on European and Middle Eastern battlefields?
Did military use of the sling die out in the middle ages? If so why?
Just how effective and were slings as weapons in ancient warfare and how were they used?
There are also many other discussions of slings in the subreddit history, though not necessarily related to when they died out. Feel free to search for those, as well.