Our only source for the reign of Olof is the ecclesiastic chronicle of
Adam of Bremen (c. 1075). Adam's information is allegedly drawn from an interview with the
Danish king
Sweyn Estridson (1047-1076) who "enumerated his forefathers". Towards the end of the 9th century Danish
Viking armies suffered a series of major defeats in the
Frankish kingdoms and in
England. This resulted in a serious loss of manpower. Frankish chronicles are silent about political conditions in Denmark in this period and up to the 930s, which contrasts with the rather regular information in the period 777-873. This possibly implies that no strong royal power existed during these decades. After the death of the Viking rulers Sigfred and Gudfred at the
battle of Leuven in 891, Denmark was, according to Adam of Bremen, ruled by a certain
Helge. Then the kingdom was attacked by an intruder named Olof, coming from the land of the
Swedes. Olof conquered the land and made himself king. No further details of his reign are given, except that he founded the
House of Olof which reigned for three generations. Later on the dynasty ended with
Sigtrygg Gnupasson who is mentioned on the two
Sigtrygg Runestones (
DR2 and
DR4) erected by his mother after his death. Sigtrygg was ousted by
Hardeknud I who inaugurated the
Jelling Dynasty. ==Historical debate==