No worries, it was not my most serious or best effort, and I may have painted with too broad a brush, and too flippant an attitude.
But I was referring less to the historical character of MacBeth than the mood and dramatic events surrounding the play. Esp the murder and betrayal part.
I admit that I put no specific research into this particular time period - if the specifics of the early 1200's were, inexplicably, a lull in the general bar fight that was early Scottish history... then my bad. Allow me a penance...
The general history of low-level lords in Scotland is hardly one of taking the moral high-road or turning the other cheek. Often during the formative years of the early Scottish nation the difference between brigandage and formal war was determined by who won the conflict (the winner always claiming they were the victims, that it was a just war, and fairly waged, ahem.) And just because one family won this generation, did not mean the issue was closed...
The larger picture was sweeping - in 1175 William the Lion* had only just sold Scotland to the English Henry for his liberty, having been captured by a freak chance after renewing the border war against England. Richard the Lionheart sold them their independence back 12 years later for the coin to go crusading, just before the turn of the century. During this time, the ecclesiastic struggles were just as tumultuous, as the Church o' England attempted to follow where the political power had shifted - and then back again. In 1214 William died, and his son, Alexander II, began a program of expanding the religious infrastructure.
(* Note that WtL was so named not for any character or act, but for putting the Lion on the Scottish flag, and that only.)
But the picture of the local lords was often independent of the overarching events. The Celtic lords and the Normans had no love for each other and often little for their own. Their feuds and troubles were the same, regardless. Galloway had rebelled outright when William was taken - this was not untypical of the attitude, that the oath of fealty was held as long as it was politically expedient.
The blood-feud, the taking of blood for blood, endured for centuries, and often a single incident echoed for generations. Homicides, for example, were very frequently pardoned by Royal grace, but "the pardon" was of no avail unless it had been issued with the full knowledge of the kin of the slaughtered man, who otherwise retained their ~legal~ right of vengeance on the homicide. There was no fixed capital - the King's (legal) Court circulated with the travels of the king. Local justice was often dictated by the whim of the baron, abbot, or the hand of the reeve on the scene.
And all this was, in fact, as TF correctly says, in a period of "relative" peace. But that peace was one in comparison to an ongoing state of war between Scotland and England - so take that "relative peace" for what it's worth.