If you read older histories of ancient Ireland, you might think the country was governed by a highly organized feudal system of high kings, regional kings and tribal kings. That's because most of the older histories took some of their sources too literally, accepting their picture of a highly structured society. The reality was not quite so organized.

The ancient Irish king or “Ri” was not so much a political ruler of a territory as a living symbol of the people's relationship to their land. In other words, the Ri was a “sacred king,” and he was believed to be married to the sovereignty goddess who represented the land. The duties of a Ri were partly symbolic and partly political. He was supposed to guarantee the fertility of the crops by observing certain arbitrary ritual taboos and carrying out other ritualized actions. Some of these actions involved actual political/military leadership, such as leading the forces of the tribe or “tuath” in its raids on other tribes.

Sometimes a battle between two tribes ended with one side in a position of clear superiority over the other. When this happened, the losing tribe would sometimes acknowledge the Ri of the winning tribe as having some sort of hypothetical authority over their own Ri. This might involve a payment of tribute (usually in the form of cattle) or an obligation to support the dominant tribe in future battles (which might or might not be honored depending on circumstances) but didn't really involve any actual political control.

If a tuath was dominant over a province or region, its Ri might describe himself as the king of that entire province, but he still had next to no authority outside of his own tribe. He was just the biggest, baddest dog in the yard, and he could expect to be respected for it- but he could not expect to be consistently obeyed. Because the ancient ritual center of Tara was considered the “omphalos” or sacred center of the entire island, the Ri who controlled Tara would sometimes claim to be “Ard Ri,” or high king of all Ireland. Because this was a coveted title, it was often fought over, but it still didn't carry any authority to actually control events outside of the Ard Ri's own tribe. Over many centuries, various Ard Ri such as the famous Brian Boru succeeded in progressively expanding the power of the institution, until it resembled a true kingship to a limited degree. An Ard Ri like Brian Boru could call upon warriors from all over the island to enforce his will- but his enemies could raise a force just as large as he could, so he still didn't exercise anything like true centralized power. Authority in the Gaelic world remained decentralized.