The Plantation of Ulster began in the 17th century when English and Scottish Protestants settled on land confiscated from the Gaelic Irish.   Prior to its conquest in the Nine Years War of the 1590s, Ulster had been the most Gaelic part of Ireland, a province existing largely outside English control.   The area was underdeveloped by mainland European standards of the time, and it possessed few towns or villages.   

Gaelic Ireland was a patchwork of independent kingdoms each ruled by a chieftain and bound by a common set of legal, social and religious traditions.    Ireland’s diocesan system was established at the Synod of Kells in the 12th century.   Following an extremely costly series of campaigns by the English, including massacre and use of ruthless scorched earth tactics, the Nine Years War ended in 1603 with the surrender of Hugh O'Neill's and Hugh O'Donnell's forces at the Treaty of Mellifont.  The terms of surrender granted to the rebels were generous, with the principal condition that lands formerly contested by feudal right and Brehon law be held under English law. 

King James I believed that colonising Ulster would quell rebellion and win over the 'rude and barbarous Irish' to 'civility' and Protestantism.   The English and Scottish planters and the role played by the London Companies in the Plantation of Ulster.   Financial backing for the Plantation of Ulster came from 12 of London’s largest livery companies. 
Plantation of Ulster
  Ireland