P. and Northmen, 7;
hunters and fishers, 8;
brochs for defence, arms, etc., 11-12;
clans, 12;
non-seafaring Celts, 12;
never conquered by Romans, 4, 12;
did not have mastery of sea in Norse times, 12;
Christian missions and Columban church, 12;
viking invasion, 13;
Pictish language superseded by Gaelic, 14, 19;