Answer
Harald Bluetooth's reign over Norway came to an end when his son, Svein Forkbeard, challenged his authority and eventually seized the throne. Svein's claim to the throne was further aided by alliances with local Norwegian chieftains who sought greater autonomy from Harald's centralized rule. Faced with a formidable coalition, Harald was compelled to relinquish his power in Norway, marking the end of his reign in the region.