Llanfihangel y Creuddyn, is an ancient parish in the upper division of the hundred (administrative division) of Ilar, Ceredigion, West Wales, 7 miles south east from Aberystwyth, on the road to Rhaiadr, comprising the chapelry of Eglwys Newydd, or Llanfihangel y Creuddyn Uchaf, and the township of Llanfihangel y Creuddyn Isaf. It was also known as Lower Llanfihangel y Creuddyn, Lower Llanfihangel y Croyddin and Lower Llanfihangel y Croyddyn. This parish is situated on the rivers Ystwyth, Mynach and Rheidol and intersected by various other streams. An ancient parish was a village or group of villages or hamlets and the adjacent lands. Originally they held ecclesiastical functions, but from the sixteenth century onwards they also acquired civil roles. The parish may have been established as an ecclesiastical parish. Originally a medieval administrative unit, after 1597 ecclesiastical units were separated from civil parishes to serve the ecclesiastical needs of the local community.

History
The lands of the parish were part of the Cistercian Abbey of Strata Florida originally established in 1164. After the Dissolution of the monasteries by Henry VIII (1536-1540) during the English Reformation, their holdings were divided and awarded to new tenants at the direction of the 1st Earl of Essex. Some of the Strata Florida lands were granted to the Herbert family, who came to Cardiganshire during the reign of Elizabeth I. One, Sir Richard Herbert of Pengelly and Cwmystwyth was High Sherriff of Cardigan from 22 November 1542.

A rent roll dated 1540 for the granges of Mefenydd, Cwmystwyth and Hafodwen (‘newe leases’) reveals that W[illia]m Herbert and Morgan Herbert were tenants of several properties formerly belonging to the Abbey of Strata Florida, including significantly: Havodychdryd Doleygors Pantycrave Bwlch Gwalter parcell of Ty Loge [...] 4 parte of Pwll Piran parte of Pregnant and Blaenmerin and Alltgron Havodychdryd or Hafod Uchtryd is the name of the house and demesne and the other properties.

Present day
Trawsgoed is the modern community (civil parish) name. Llanfihangel translates as the church of St. Michael (Welsh: Mihangel). The parish lies within the Cistercian Way. The area is now sparsely populated with only a few towns and villages such as Ysbyty Ystwyth, Cwm Ystwyth, Pont rhyd y groes, Llanilar and Llanfarian. In the past area was relatively densely populated due to its mineral wealth. Silver, lead and zinc have been mined in the valley since Roman times, an activity that reached its peak in the 18th century. The largest of the very many mines was Cwm Ystwyth Lead Mine.

Within the boundaries of the parish lies the village of Llanfihangel y Creuddyn, the Hafod Estate and Devil's Bridge.