- The Ulaid: The Ulaid were a powerful tribe that controlled much of the northern part of Ireland. Their capital was at Emain Macha, which is located in present-day County Armagh.
- The Connachta: The Connachta were a tribe that controlled much of the western part of Ireland. Their capital was at Cruachan, which is located in present-day County Roscommon.
- The Érainn: The Érainn were a group of tribes that controlled much of the southern and eastern parts of Ireland. Their capital was at Tara, which is located in present-day County Meath.
- The Laigin: The Laigin were a tribe that controlled much of the southeastern part of Ireland. Their capital was at Dún Laoghaire, which is located in present-day County Dublin.