The tríocha céad, also known as trícha cét, meaning "thirty hundreds", was a unit of land-holding in eleventh and twelfth century Ireland.^[1][2] The term appears to relate to the number of troops an area could raise.^[1]

Described as a "spatial unit of royal tenure, taxation, local government, and military levy", the trícha cét largely corresponded to a local petty kingdom ruled by a petty king.^[3] A minority, however, were ruled by a taisaig (leader) or an airríg (governor), appointed by a superior kings.^[3]

In the province of Ulster, a tríocha céad was subdivided into roughly twenty-eight baile biadhtaigh, meaning "lands of a food-provider", and around 463 seisrigh, meaning "six-horse plough-teams".^[1]

During the eleventh century, the system became established across the island, a refinement on a pre-existing system.^[3]

• Townland
• Carucate
• Túath

• MacCotter, Paul (2008). Medieval Ireland: Territorial, Political and Economic Divisions. Four Courts Press. ISBN 978-1-84682-098-4.

• The Triocha Céts