ulster scots are an ethnic group in ireland, descended from lowland scots and english from the border of those two countries, were "border reivers". these people first began to occupy ireland in large numbers with the plantation of ulster, ordered by james i of england on land taken from the irish nobility, mostly in the province of ulster. the term "ulster-scots" refers to both these colonists of the 17th century and, less commonly, to the gallowglass who began to arrive from what is now northwest scotland centuries earlier.