In earlier times the townland was probably uninhabited as it consists mainly of bog and poor clay soils. It was not seized by the English during the Plantation of Ulster in 1610 or in the Cromwellian Settlement of the 1660s so some dispossessed Irish families moved there and began to clear and farm the land. A deed by Thomas Enery dated 29 Jan 1735 includes the lands of
Knockgorrum. A deed by John Enery dated 13 December 1774 includes the lands of
Knockgarrim otherwise Knockgarrin. The 1790 Cavan Carvaghs list spells the name as
Knockgorm. The Tithe Applotment Books for 1826 list six tithepayers in the townland. The Ordnance Survey Name Books for 1836 give the following description of the townland-
Contains 351 acres, 319 of which are rough mountain pasture...lime stone can be procured but it is not quarried nor used in any way whatever. The Knockgorm Valuation Office Field books are available for August 1839.
Griffith's Valuation of 1857 lists four landholders in the townland. In the 19th century the landlord of Knockgorm was the Hassard Estate. In 1875 the Hassard Estate sold Knockgorm to James Bracken. ==Census==