Iarmhumhain (older spellings: Iarmuman, Iarmumu or Iarluachair) was a Kingdom in the early Christian period of Ireland in west Munster.
Its ruling branch was called the Eóganacht Locha Léin or Ui Chairpri Lúachra.
The name Iarluachair means west of the Sliabh Luachra mountains.
They ruled over smaller kingdoms in west Munster such as the Ciarraige Luachra, Corcu Duibne and Corcu Loígde and at the height of their power may have ruled over areas of west Thomond including the Corcu Baiscinn and Corco Mruad and perhaps even had some sovereignty over the Uí Fidgenti of County Limerick and the Eóganacht Raithlind of County Cork.
The transference of the overlordship of the Ciarraige Luachra to direct Cashel control in the reign of Feidlimid mac Cremthanin (died 846) signified this.