In Kansai-ben, ねん, てん, ん, のん, and たん are used in queries, asking for reasons, and giving explanations.
The standard sentence endings のだ and んだ may become ねん and てん in Kansai-ben. The main difference between the two is that while ねん is mainly used in the non-past tense, てん is always used in the past tense.