The balance of power between these different groups changed over time. Early in the period, kings were elected by members of the late king's council, but primogeniture rapidly became the norm for succession. The kings further bolstered their status by adopting Christian ceremonies and nomenclature, introducing ecclesiastical coronations during the 8th century and terming themselves "Christ's deputy" by the 11th century. Huge estates were initially built up by the king, bishops, monasteries and "thegns", but in the 9th and 10th centuries these were slowly broken up as a consequence of inheritance arrangements, marriage settlements and church purchases. In the 11th century, the royal position worsened further, as the "ealdormen" rapidly built up huge new estates, making them collectively much more powerful than the king—this contributed to the political instability of the final Anglo-Saxon years. As time went by, the position of the "churls" deteriorated, as their rights were slowly eroded and their duties to their lords increased.