Historically Tyrone stretched as far north as Lough Foyle, and comprised part of modern day County Derry east of the River Foyle. The majority of County Derry was carved out of Tyrone between 1610 – 1620 when that land went to the Guilds of London to set up profit making schemes based on natural resources located there. Tyrone was the traditional stronghold of the various O’Neill clans and families, the strongest of the Gaelic Irish families in Ulster, surviving into the seventeenth century. The ancient principality of Tír Eoghain, the inheritance of the O’Neills, included the whole of the present counties of Tyrone and Derry, and the four baronies of West Inishowen, East Inishowen, Raphoe North and Raphoe South in County Donegal.