=10. Union of Picts and Scots.=--This union took place under _Kenneth MacAlpin_, who was king of the Scots. That he was king of the Picts also is certain: how he came to be so can only be guessed. It is more probable that it was by inheritance than by conquest, though he and the kings after him kept his original title of King of Scots. Over how much land he reigned, and what degree of power he had over his subjects, is not known. It is thought that among the Celts the king was only the head of the dominant tribe among many other tribes or clans, each of which was bound to follow its own chief, and the king's control over those chiefs seems to have been more in name than in fact. The northern districts seem to have been ruled by powerful chiefs called _Maers_ or _Mormaers_. These chiefs, who it has been supposed were nominally subject to the King of Scots, acted as if they were quite independent of him. They were indeed his most troublesome enemies, and several of the kings lost their lives in battle against them. _Moray_ was the greatest of the Mormaerships. It lay north of the Spey and of the mountains of Argyle, and stretched across the country from the Moray Firth to the opposite ocean. =11. Coming of the Northmen.=--Kenneth was followed in turn by _Donald_, his brother, and _Constantine_, his son. Their reigns were mainly taken up in fighting with the _Northmen_, a heathen people of Teutonic race, who infested the seas and plundered the seaboard. From the eighth century downwards they were the scourge alike of English and Celtic Britain, swooping down on the coasts, harrying the lands, and making off with their booty; or, at other times, seizing and settling on great tracts of country. Three countries of modern Europe--_Denmark_, _Norway_, and _Sweden_ were peopled by the Northmen. But while it was those from _Denmark_ who chiefly harassed and finally conquered the _English_, the _Norwegians_ seem to have looked upon Scotland as their own especial prey, attracted doubtless by the likeness between its many isles and inlets and the jagged outline of the larger Scandinavian peninsula. The long narrow lochs of the western coast, like the fiords of Norway, proved convenient harbours for the ships of these pirates. It is towards the close of the eighth century that we first hear of the descents of the Northmen on the Pictish kingdom. It is told how they ravaged all the coast, destroyed the Pictish capital, and haunted the Irish Sea. Their fury was specially directed against churches and religious communities, and Iona did not escape. Again and again it was wasted by fire and sword, its churches plundered, the brethren slain, till at length the abbot was compelled to seek on the mainland a refuge for himself and the relics of the saintly founder. Under Kenneth MacAlpin the supremacy over the Scottish Church was transferred to the monastery of _Dunkeld_. Under Kenneth's son, _Constantine I._, a fresh spirit was given to these invasions by