Tassan is a townland in the parish of Clontibret in County Monaghan, Ireland. The townland of Tassan or Tasson is situated approximately two miles north east of Annyalla, close to the border with Northern Ireland, between the towns of Monaghan and Castleblayney, off the old N2 primary road, which linked Dublin and Derry. The area is located close to the …Tassan is a townland in the parish of Clontibret in County Monaghan, Ireland. The townland of Tassan or Tasson is situated approximately two miles north east of Annyalla, close to the border with Northern Ireland, between the towns of Monaghan and Castleblayney, off the old N2 primary road, which linked Dublin and Derry. The area is located close to the Armagh border which provided an option for people to make a living during periods of economic recession also the Cashel and Tonagh bogs supplied a source of fuel to people for many years up to the late 1960s. Two lakes dominate the landscape in the townland, Lough Nahinch and Tassan Lough Natural Heritage Area, both of which have been used by anglers for pike and perch fishing over the centuries.