The origin of this tradition dates back to the Edo period.
The cause of the accident was a small mistake.
If you trace the origin of this festival, it goes all the way back to the Edo period.
A small misunderstanding became the origin of a big conflict.
発端 stresses the specific incident that triggers a chain of events, while 起こり can refer more generally to the root or start of something.
由来 focuses on the background history behind a name or custom, while 起こり points more simply to the moment or cause something began.
Standard spelling; the most common written form.
Less common variant; acceptable but 起こり is preferred.
Irregular okurigana usage; rarely used in modern writing.
Noun form of the verb 起こる (to occur, to happen), from the stem 起こり. The kanji 起 means 'to rise' or 'to start'.