Tashlich
 

I'm curious where this tradition originated. I know it is practiced by both Ashkenazi and Sephardic communities, so I'm assuming it goes back quite a way. Does anyone know where it originated?

The basic answer is we do not know. It is not mentioned in the Tanakh nor in the Talmud, either Talmud.

The earliest known reference to it goes back to, if memory serves me right, around 1425, which would probably put its origins somewhere in the 1300s.

L'shalom,

Peter