Human habitation of the region of Pembrokeshire extends back to 125,000 and 70,000 BCE. By the late Roman Empire period, an Irish tribe known as the Déisi settled in the region between 350 and 400, with their realm known as Demetae. In the post Roman period, the Irish Déisi merged with the local Welsh, with the regional name underlying Demetae regularly evolving into Dyfed, which existed as an independent petty kingdom until its heiress, Elen, married Hywel Dda in 904. Hywel merged Dyfed with his own maternal inheritance of Seisyllwg, forming the new realm of Deheubarth.The region suffered from devastating and relentless Viking raids during the Viking Age, with the Vikings establishing settlements and trading posts at Haverfordwest, Fishguard and Caldey Island. Pembroke Castle, birthplace of Henry VII Dyfed, the region of Pembrokeshire, remained an integral province of Deheubarth but this was contested by invading Normans and Flemings who arrived between 1067 and 1111.The region became known as Pembroke (sometimes archaic Penbroke), after the Norman castle built in the cantref of Penfro. But Norman/Flemish presence was precarious given the hostility of the native Welsh Princes. In 1136 Prince Owain Gwynedd sought to avenge the execution of his sister, Gwenllian ferch Gruffydd, and her children; with Gwenllian's husband the Prince Rhys swept down from Gwynedd with a formidable army and at Crug Mawr near Cardigan met and destroyed a 3,000-strong Norman/Flemish army. The remnants of the Normans fled across the bridge at Cardigan which collapsed and the Teifi river was choked with drowned men-at-arms and horses. Owain's brother Cadwallader took de Clares daughter Alice as his wife. Owain incorporated Deheubarth into Gwynedd, re-establishing control of the region. Mortally weakened Norman/Flemish influence never fully recovered in West Wales. Princess Gwenllian is one of the best remembered victims. In 1138 the county of Pembrokeshire was named as a county palatine. Proportion of Welsh speakers (2011 census) The county has long been divided between an English-speaking south (known as "Little England beyond Wales") and a historically more Welsh-speaking north, along a reasonably sharply-defined linguistic border called the Landsker Line. Rhys ap Gruffydd, Gwenllian's son, reestablished Welsh control over much of the region and threatened to retake all of Pembrokeshire, but died in 1197. After Deheubarth was split by a dynastic feud, Llywelyn the Great almost managed to retake the region of Pembroke between 1216 and his death in 1240. In 1457 Henry Tudor was born at Pembroke Castle and, 28 years later, landing an army not far from his birthplace, he rallied support, marched through Wales to Bosworth field in Leicestershire and defeated the larger army of Richard III at the Battle of Bosworth Field. As Henry VII of England, he founded the House of Tudor, a dynasty that successfully ruled England until 1603. The Laws in Wales Act 1535 divided the county into hundreds, which followed with some modifications the boundaries of the cantrefs, ancient jurisdictions which went back to before the Norman conquest. The 1536 hundreds were (clockwise from the northeast): Cilgerran Hundred or Kilgerran, Cemais or Kemes, Dewisland or Dewsland, Roose Hundred, Castlemartin Hundred, Narberth Hundred and Dungleddy (Daugleddau). The GENUKI web pages on Pembrokeshire include a list of the parishes within each hundred. During the First English Civil War (1642-1646) the county gave strong support to the Roundheads (Parliamentarians), in sharp contrast to the rest of Wales, which was staunchly Cavalier (Royalist). In spite of this an incident in Pembrokeshire triggered the opening shots of the Second English Civil War when local units of the New Model Army mutinied. Oliver Cromwell defeated the uprising at the Siege of Pembroke in July 1648. In 1649 the Cromwellian conquest of Ireland began when its forces sailed from Milford Haven. There has been considerable military activity in Pembrokeshire from the Civil War to the Cold War with, for example, military exercises in the Preseli Hills and a number of former military airfields.Military and industrial targets in the county were subjected to bombing during World War II. In 1791 a petition was presented to the House of Commons concerning the poor state of many of the county's roads, pointing out that repairs could not be made compulsory by the law as it stood. The petition was referred to committee. There are many known shipwrecks off the Pembrokeshire coast. The county has six lifeboat stations, the earliest of which was established in 1822; in 2015 a quarter of all Royal National Lifeboat Institution Welsh rescues took place off the Pembrokeshire coast.