Halfdan was a year old when his father was killed, and his mother Aase set off immediately with him westwards to Agder, and set herself there in the kingdom which her father Harald had possessed. Halfdan grew up there, and soon became stout and strong; and, by reason of his black hair, was called Halfdan the Black.
About 800 ad. Norwegian, local king, according to the sagas son of Gudrrd Veidekonge (traveling king), who was of the Ynglinge-clan. Halfdan inherited the northern part of Vestfold and conquered Opplandene and Viken (inner part of Oslofjord). Drowned after falling through the ice in the Lake Randsfjorden. Halfdan was the father of Harald Fair-hair. The story about Halfdan is historically uncertain.
The encyclopedia "Kunnskapsforlaget" estimates that Halfdan must have drowned before 850. This does not match their own record on his son, Harald, who they estimate to have been born around 865. The battle of Hafrsfjord supposedly took place about 872, according to the celebration and the monument by Hafrsfjord. Harald must then have been an adult, so he was probably born before 850.
Halfdan the Black got a wife called Ragnhild, a daughter of Sigurd Hjort, a strong and handsome King in Ringerike and his wife Thorney, who was a daughter of a king in Jutland.. They had a son, to whom Harald gave his own name; and the boy was brought up in Sogn, by his mother's father, King Harald. Now when this Harald had lived out his days nearly, and was becoming weak, having no son, he gave his dominions to his daughter's son Harald, and gave him his title of king; and he died soon after. The same winter his daughter Ragnhild died; and the following spring the young Harald fell sick and died at ten years of age. As soon as Halfdan the Black heard of his son's death, he took the road northwards to Sogn with a great force, and was well received. He claimed the heritage and dominion after his son; and no opposition being made, he took the whole kingdom.
Sigurd Hjort was the name of a king in Ringerike, who was stouter and stronger than any other man, and his equal could not be seen for a handsome appearance. His father was Helge Hvasse (the Sharp); and his mother was Aslaug, a daughter of Sigurd the worm-eyed, who again was a son of Ragnar Lodbrok. It is told of Sigurd that when he was only twelve years old he killed in single combat the berserk Hildebrand, and eleven others of his comrades; and many are the deeds of manhood told of him in a long saga about his feats. Sigurd had two children, one of whom was a daughter, called Ragnhild, then twenty years of age, and an excellent brisk girl. Her brother Guthorm was a youth. It is related in regard to Sigurd's death that he had a custom of riding out quite alone in the uninhabited forest to hunt the wild beasts that are hurtful to man, and he was always very eager at this sport. One day he rode out into the forest as usual, and when he had ridden a long way he came out at a piece of cleared land near to Hadeland. There the berserk Hake came against him with thirty men, and they fought. Sigurd Hjort fell there, after killing twelve of Hake's men; and Hake himself lost one hand, and had three other wounds. Then Hake and his men rode to Sigurd's house, where they took his daughter Ragnhild and her brother Guthorm, and carried them, with much property and valuable articles, home to Hadeland, where Hake had many great farms. He ordered a feast to be prepared, intending to hold his wedding with Ragnhild; but the time passed on account of his wounds, which healed slowly; and the berserk Hake of Hadeland had to keep his bed, on account of his wounds, all the autumn and beginning of winter. Now King Halfdan was in Hedemark at the Yule entertainments when he heard this news; and one morning early, when the king was dressed, he called to him Harek Gand, and told him to go over to Hadeland, and bring him Ragnhild, Sigurd Hjort's daughter. Harek got ready with a hundred men, and made his journey so that they came over the lake to Hake's house in the grey of the morning, and beset all the doors and stairs of the places where the house-servants slept. Then they broke into the sleeping-room where Hake slept, took Ragnhild, with her brother Guthorm, and all the goods that were there, and set fire to the house-servants' place, and burnt all the people in it. Then they covered over a magnificent wagon, placed Ragnhild and Guthorm in it, and drove down upon the ice. Hake got up and went after them a while; but when he came to the ice on the lake, he turned his sword-hilt to the ground and let himself fall upon the point, so that the sword went through him. He was buried under a mound on the banks of the lake. When King Halfdan, who was very quick of sight, saw the party returning over the frozen lake, and with a covered wagon, he knew that their errand was accomplished according to his desire. Thereupon he ordered the tables to be set out, and sent people all round in the neighborhood to invite plenty of guests; and the same day there was a good feast which was also Halfdan's marriage-feast with Ragnhild, who became a great queen.
King Halfdan was a wise man, a man of truth and uprightness -- who made laws, observed them himself, and obliged others to observe them. And that violence should not come in place of the laws, he himself fixed the number of criminal acts in law, and the compensations, mulcts, or penalties, for each case, according to every one's birth and dignity (1).
Queen Ragnhild gave birth to a son, and water was poured over him, and the name of Harald given him, and he soon grew stout and remarkably handsome. As he grew up he became very expert at all feats, and showed also a good understanding. He was much beloved by his mother, but less so by his father.
Halfdan the Black was driving from a feast in Hadeland during the great thaw in the spring of about 860, and it so happened that his road lay over the lake called Rand. It was in spring, and there was a great thaw. They drove across the bight called Rykinsvik (Randsfjord), where in winter there had been a pond broken in the ice for cattle to drink at, and where the dung had fallen upon the ice the thaw had eaten it into holes. Now as the king drove over it the ice broke, and King Halfdan and many with him perished. He was then forty years old. He had been one of the most fortunate kings in respect of good seasons. The people thought so much of him, that when his death was known and his body was floated to Ringerike to bury it there, the people of most consequence from Raumarike, Vestfold, and Hedemark came to meet it. All desired to take the body with them to bury it in their own district, and they thought that those who got it would have good crops to expect. At last it was agreed to divide the body into four parts. The head was laid in a mound at Stein in Ringerike, and each of the others took his part home and laid it in a mound; and these have since been called Halfdan's Mounds. (Note: It is believed that Halfdan’s half-brother, Olav Gierstad Alv, is the Viking King who was buried in his ship at Godstad. This ship was excavated in 1890 and can be seen at the Viking Ship Museum in Oslo.)
Halfdan Svarte was King of Norway from 839-860 when he died. In the 800's the bloody conflicts between tribal kingdoms, as well as a craving for adventure, prompted Norwegians to leave their lands in what are known as Viking voyages. Warriors from the Viks, or fjords, raided throughout western Europe and into the Mediterranean.
Another version:
Halfdan Svarte married Ragnhild whose father was Sigurt Hjort. Sigurd Hjort was a king in Ringerike. He was bigger and stronger than any man. He was also more handsome than most others. His father was Helge the bright, and his mother, Cslaug, daughter of Sigurd Snake-in-eye, son of Ragnar Lodbrok. They say that when he was 12 years old, he singlehandedly killed Hildebrand Berserk and 11 men of the same kind. He performed many other manly deeds, and the story of him is long. He had two children: the daughter, Ragnhild, an extraordinarily beautiful woman, she was in her twenties at the time, and her brother, Guttorm, was in his teens. About how Sigurd Died , this is said; He rode alone into the wild forest as he used to, chasing large and dangerous animals, something he liked to do and did often. When he had ridden far, he reached a clearing some place near Hadeland, and Hake Berserk came towards him with 30 men. They fought, and there fell Sigurd Hjort and 12 of Hake's men. And Hake himself lost an arm and had three other wounds. Afterwards he rode to Sigurd's farm and took Ragnhild, his daughter, and Guttorm, her brother, away and looted a lot of gold and silver and many expensive things and took them home to Hadeland, where he had large farms. Then he threw a party and wanted to marry Ragnhild, but it was put off, as his wounds got worse. Hake Haldingberserk's wounds kept him in bed the whole fall and the first part of winter.
Source:
http://valh.sasktelwebsite.net/family/bc65.html