Magh Slécht (sometimes Anglicised as Moyslaught) is the name of a historic plain in Ireland. It comprises an area of about three square miles (8 km2) situated in the south-eastern part of the Parish of Templeport, Barony of Tullyhaw, in the west of County Cavan. It is bounded on the south by Templeport Lough, on the north by Slieve Rushen mountain, on the east by the Shannon–Erne Waterway, and on the west by the River Blackwater. Magh Slécht formed part of the Province of Connacht until the 16th century when it was made part of the Province of Ulster.It was originally named Magh Senaig (plain of the hill-slope) and under this guise is mentioned in The Metrical Dindshenchas in the story of the Dagda, Corrgenn and Ailech, wherein it states the Corrgenn travelled from Tara to Lough Foyle in the Inishowen peninsula via Mag Senaig.
In Pre-Christian times the small area where the Crom Cruach idol stood at Killycluggin and Kilnavert was originally named Fossa Slécht or Rath Slécht and it is from this small location that the wider Magh Slécht area received its name. In 1911 BC during the reign of Fodbgen, the Firbolg High-King of Ireland, the name Magh Senaig was changed to Magh Slécht (The plain of prostrations) as it became the nationwide centre of the cult of the god Crom Cruach. Another interpretation is Magh Sleacht meaning the Plain of the Monument.
St. Patrick is said to have thrown down Crom Cruaich when he stretched out the Bachal Isu from a neighbouring hill causing it to fall over with its head pointing toward the Hill of Tara. The twelve surrounding idols were then swallowed up by the earth.Another name for the plain was Magh Lecet or Magh Leced. The ancient Irish prayed by prostrating themselves in a similar fashion to today's Muslims, i.e. by kneeling down on both knees and touching the forehead against the earth. The plain is not flat but consists of little drumlin hills. However, as it is surrounded by mountains, it is a plain in comparison. In the old Irish tale The Siege of Druim Damhgaire or Knocklong (Forbhais Droma Dámhgháire), one of King Cormac Mac Art's druids was called Cecht of Magh Slécht.
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