Túath (plural túatha) is the Old Irish term for the basic political and jurisdictional unit of Gaelic Ireland.
There was a hierarchy of túatha statuses, depending on geographical position and connection to the ruling dynasties of the region.
[5] The trícha céta were primarily for reckoning military units; specifically, the number of fighting forces a particular population could rally.
Whereas in cases like Ulster, which involved large scale colonisation and confiscation of land, the shape of the original divisions is not always clear or recoverable.
[7][8] In Modern Irish it is spelled tuath, without the fada accent, and is usually used to refer to "rural districts" or "the country" (as in "the countryside", in contradistinction to "the city"); however the historical meaning is still understood and employed, as well.