The township is named after an older variant spelling of Moyallen, County Down, now in Northern Ireland.

[4] Waltersburg, Keisterville, Upper Middletown, Searights, Buffington, New Salem, Haddenville, Shamrock, Upper Peanut, Lower Peanut, Dearth, Rocks Works, Newboro, and portions of Smock and Balsinger are located in this township.

The township is in west central Fayette County and is bordered to the northeast by Redstone Creek, a tributary of the Monongahela River.

The expressway can be accessed from Exit 18 in Menallen Township, serving Keisterville.

About 1,200 customers are connected to public sewage treatment systems throughout the township.

This facility was constructed to collect fees from travelers on the National Road in the 19th century.

The Smock Historic District, Searights Tollhouse, National Road, Abel Colley Tavern and Josiah Frost House are listed on the National Register of Historic Places.