About 840AD the Celtic King Kenneth I (reigned 843-58) united the tribal Picts and the Scots and formed a kingdom in central Scotland. Later kings expanded the realm to include Strathclyde and Lothian. This Celtic monarchy lasted until Macbeth's bloody reign ended (1057); he was killed and replaced by Malcolm III. Under Malcolm and his successors, especially King David I (reigned 1124-53), Scotland became an organized feudal state | About 840AD the Celtic King Kenneth I (reigned 843-58) united the tribal Picts and the Scots and formed a kingdom in central Scotland. Later kings expanded the realm to include Strathclyde and Lothian. This Celtic monarchy lasted until Macbeth's bloody reign ended (1057); he was killed and replaced by Malcolm III. Under Malcolm and his successors, especially King David I (reigned 1124-53), Scotland became an organized feudal state |