[dorfsmay]

"Among Celtic and Germanic peoples, the predominant custom during ancient times seems to have been to divide the land in equal parts for each of the sons." (1)

Which also applied to countries and why Western Europe kept going from a unified empire to a bunch of countries. The last time this happen was in 843 "When Louis the Pious died in 840, his eldest son, Lothair I, claimed overlordship over the whole of his father's kingdom .../... Lothair's brother Louis the German and his half-brother Charles the Bald refused to acknowledge Lothair's suzerainty and went to war against him. .../... after which Lothair became willing to negotiate a settlement." (2).

1: https://en.wikipedia.org/wiki/Historical_inheritance_systems...

2: https://en.wikipedia.org/wiki/Treaty_of_Verdun