The Portadown area had long been populated by Irish Gaels. At the beginning of the 1600s, it lay within the district of Clancann ("Clann Chana"), which was part of the larger territory of Oneilland ("Uí Nialláin"). This district was named after the dominant local clan—the McCanns ("Mac Cana")—who had been in the area since before the 13th century. The McCanns were then a vassal sept of the O'Neills ("Uí Néill"). On the eastern banks of the River Bann was the district of Clanbrasil ("Clann Bhreasail").