This is event is performed to dispatch the souls of the ancestors ??? and is said to have over 300 years of history.
I'm struggling to parse this sentence. In particular how should I fit お盆が終わって into it?
I cannot make a parsing which contains "Obon ends and...".
The only parsing I can make which makes sense is to have お盆が終わって adverbially modify 行う i.e "the event is performed by means of Obon ending.", but I'm not finding that at all convincing.
Or maybe it could adverbially modify 送る to give "This event is performed to dispatch the souls of the ancestors by Obon ending", i.e. Obon ending is the thing that brings about the dispatch of the souls. I find this only marginally more convincing.
I keep trying to make it say "This is event is performed to end Obon and dispatch the souls of the ancestors", but surely that would require the transitive version: お盆を終えて.