The parish of Tyholland is bounded on the north and north west by the parish of Donagh and on the south and south west by the parish of Monaghan while Clontibret parish lies to the south east. It is approximately four miles in length and breadth and contains almost 6,000 acres divided into 56 townlands originally known as tates. The River Blackwater marks the northern boundary of the parish and the Corr River the western boundary while the Ulster Canal cuts a path through its middle from east to west. Some of its eastern boundary forms part of the border between the Republic of Ireland and Northern Ireland. There are no towns within the perimeters of the parish, however Monaghan town is close to the south west and Glaslough to the north.
The area is low lying with a scattering of drumlins deposited during the Ice Age and crossed by small streams some of which emanate from a small lake Shelvins Lough. Some woodland is marked on the present day map in the Drumgoole/Corvally and Garran Itra/Annacramph areas. In the past the area produced linen, bricks and grain. Evidence of this can be found in the Ordnance Survey Place Name Book for ‘Tehollin’ dated 1835, which records an ‘excellent corn mill in Clonlonan’ and another at Dromore, a flax mill in Seavagh and a brick field in Skinnagin. Limestone was burnt in Carrowkeel and sold at 16d a barrel while Dromore had a good limestone quarry.
The name of the parish ‘Tyholland’ is derived from the name Ti or Tigh Thalen, the house of Tallen, as identified by Jack Storey in his ‘Tyholland Church of Ireland Records – St Cillian’s’, (Clones Library), who gives variations of the spelling of the name from 1432 to the mid-1880s, while the townland website Logainm traces the name from the eighth century. The Rev Thomas Walsh in his History of the Irish Hierarchy with the Monasteries of each county, published in 1854, refers to St Tellan, son of Colgan, a chief of the district who gave his name to the church of Tehallan. He also mentions St Killen, a bishop ‘some say was placed there by St Patrick’. The parish name was certainly spelt in a variety of ways in the eighteenth and nineteenth centuries Tehallan/Tehallen/Tehollin/Tyhallan until about 1837 when it changed to Tyholland. However, there are earlier instances of the parish name being spelt with a ‘d’ at the end, for example this was the spelling used by the Rev Edward Stanley when he wrote up the vestry minutes between 1807 and 1811. The change in 1837 may have been influenced by the appointment of a new minister the Rev John Rotheram Tarleton. Nowadays, both the Protestant and Catholic parishes use this spelling although the civil parish is still spelt Tehallan. Why a ‘d’ was inserted at the end of the name of the church parishes is unknown.