Mac Siúrtáin, aka Mac Jordan and Jordan, is the name of a Connacht family of Norman-Irish origins.
The family take their name from the Norman knight, Jordan de Exeter, whose descendants became known as Mac Siúrtáin - the Gaelic form of Jordan - and were based in County Mayo.
The de Exeter's were originally from the town of Exeter, Devon, and are recorded in Dublin and Meath from the 1230s onwards. They included Henry de Exeter, Mayor of Dublin c.1240-41; Michael d'Exeter, Bishop of Ossory 1289–1302; Richard de Exeter, killed 1287; Sir Richard de Exeter, died 1327; and Sir Stephen de Exeter, fl. 1280–1316.
The descendants of Jordan de Exeter settled in Connacht, mainly in what is now County Mayo. The territory they conquered, Gailenga (later known as the barony of Gallen), was the southern part of Luighne (also known as Sliabh Lugha), whose lords were the clan Ó Gadhra. The de Exeters expelled the Ó Gadhras into Coolavin, County Sligo, while the clan Ó hEaghra retained the name Luighne for their territory to the north.
Becoming steadily Gaelicised over a number of generations, the family as a whole were known as the Mac Siúrtáin (or Mac Jordan, i.e., the sons of Jordan). Only the chief of the clan was entitled to be called de Exeter.
John de Exeter/John na Conairte Mac Jordan is commonly believed to be the common ancestor of all Jordans of Connacht, except for a family called Mac Jordan Duff, descended from Jocelyn de Angulo.
Stephen, dead by 1280. Jordan, fl. 1239–58. John de Exeter, died 1261. =Johanna, alive 1280. =Basilia, fl. 1253 | | | | | |___________________ Richard de Exeter, d. 1287. Sir Stephen, d. 1316 | | | =Matilda, fl. 1318. | | |_________________ | Meiler, k. 1289. Jordan Óge | | | | | | | Sir Stephen, fl. 1302. | ____| Sir Richard John, b.1270 Meiler, k. 1317. | | | | | |__________________ John na Conairte Jordan Bacach | | | | | | Simon Richard of Derver Clan Jordan of Mayo fl.1335 fl. 1347.