I read this sentence in a book for beginners, but I can't find the grammar in any of my books or online:
Which I translate as
While the old woman was washing in the river, a big peach came floating down from upstream (with some sound effects).
However, I can't find any references that mention that the verb in -ている form followed by と should mean "while". Or indeed any references to such a construct at all. Can someone please explain this grammar, how common it is, and when it is right to use it? Note that I am familiar with the verb-ている form when referring to "verb-ing" or when there is a change of state. I'm also happy that と after a verb can mean "if", but that doesn't seem to work here.