Bretislaus I, Duke of Bohemia, is the author of decrees concerning the rules of Christianization, which include a ban on polygamy and trade on holidays.

It was in 1030 that Bretislaus had married Judith of Schweinfurt.

In 1054, Bretislaus organizes the succession and issues the famous Seniority Law, introducing agnatic seniority for order of succession.

Younger members of the dynasty are supposed to govern fiefs (technically, parts of Moravia), but only at the Duke's discretion.

The result of this institution will be the relative indivisibility of the Czech lands, but also the alternation of rules of stronger (or perhaps more political) dukes with periods of bitter fraction wars of members of the dynasty.

It will be effectively ended by the elevation of Bohemia to kingdom under Ottokar I of Bohemia, when primogeniture will become the ruling principle.

Bretislaus’s eldest son Spytihněv is to succeed him as Duke of Bohemia with control over that territory.

Moravia is incorporated into the Bohemian duchy, but divided between three of his younger sons.

The Olomouc Appanage goes to Vratislaus; the Znojmo Appanage goes to Konrád; and the Brno Appanage went to Otto.

The youngest son, Jaromír, enters the church and becomes Bishop of Prague.