For those who don’t know, the Kansai dialect is prevalent in and around Osaka, Kyoto and Kobe. One of the major features of the dialect is changing negative ending from ない to へん like this:
できない → できへん
わからない → わからへん
There’s more detailed information here, but the site makes no mention of why exactly they do this or how it came about. I’m sure there are longer, more extensive reasons it developed that way, but it’s interesting that the dialect has what is essentially a ない-replacer.