McKay, P A Dictionary of Ulster Place-names (Belfast, 1999) notes:
3 kilometres south of Markethill
Parish of Loughgilly, Barony of Fews Lower
From the Irish Ma Bhan 'White Plain'
Mowhan stands on the Mowhan River and links the townland of Drumgane with the townland of Kilbracks in the neighbouring Parish of Kilcluney.
In the accompanying audio recording, Ivan Walker talks about the settlement of Mowhan.
Use the audio controller to listen to this talk, given in 2003.