Capel Llangynheiddon is mentioned in documents of the twelfth century and is said to have been a chapel of ease to Llandefeilog. It is thought to have been situated at the southern end of Mynydd Cyfor, in the north-west angle formed by the cross roads at the hamlet of Bancycapel. Some mounds of earth are said to mark the site of the chapel. The site is depicted on hisoric (1888-1906) Ordnance Survey mapping. It is possible that a fifth road converged on the cross roads from a westerly direction. The chapel is thought to have still been standing at the turn of the 18th century. According to local tradition, Llangynheiddon's bell was removed to St Cain's Church, Llangain (NPRN 12664), some 4.6km to the west, when the former fell into disuse. A standing stone (NPRN 308725) is situated some 580m to the east of the chapel site.

Sources include:
Ordnance Survey, 1888, first edition 25inch
Ordnance survey, 1906, second edition 25 inch

N Vousden, RCAHMW, 17 September 2012