(and why people in England around AD 750-800 would have cared about it)
In the Fifth Century, the Danes – whose original homeland was in Scania (the southern tip of Scandinavia, only taken over by Sweden in the Seventeenth Century) – were expanding westward into the islands and onto the Jutland peninsula. There were several tribes of Danes involved, with no central monarchy to encompass them all. Widsith mentions Sea-Danes, Hocings, South-Danes, Danes (not further defined), as well as various related peoples.
Hoc, also called Healfdene, indicating an origin on the fringes of Danishry – somebody with a “colonial” pedigree, not from Scania – leads a tribe of Danes which has been expanding at the expense of the Jutes. By the time his son, Hnaef Hocing, is ruling the kingdom, the Jutes have lost their independence. The last prince of the Jutes, Garulf son of Guthulf (Gefwulf?) is in refuge at the court of Finn Folcwalding, king of Frisia.
It is part of the Hocings’ diplomacy to cultivate a relationship with the Frisians, in part in order to pressure the Jutes, who dwell between them. Hnaef’s sister Hildeburh is married to Finn, and their son Frithuwulf has been fostered at Hnaef’s court. When Hnaef comes to return Frithuwulf to the court of Finn, trouble breaks out among the exiled Jutes in both entourages. The refugee Jutes around Garulf attack Hnaef’s party, which includes a Jutish turncoat (in their eyes) named Hengest.
In the slaughter which follows, Garulf, Hnaef, and Frithuwulf are all slain. Hengest and the remaining Danes negotiate a truce with Finn until they can clear out in the spring. By then, Hengest accepts the need to avenge Hnaef and stays behind to lull Finn into a false sense of security while Hnaef’s Danish retainers return home and get up a raiding party. When they return, Hengest opens the gates to them, and Finn’s stronghold is sacked. Finn dies in the attack. His second son, Frealaf, escapes the slaughter and reigns after him in Frisia.
All this matters to Old English audiences for two reasons. First, Hengest the Jutish rover and his brother Horsa are the traditional mercenaries brought in by Vortigern who betray him and seize the land of Kent. The Anglo-Saxon invasions begin with them. Second, next door to the Jutes, the Frisians, and the Danes are the Angles under Offa, from whom the Anglian invaders of Mercia, Northumbria, and East Anglia came.
Hnaef has another sister, whose son Healfdene becomes king. His father is not a king. He is provided a mythical genealogy, as the son of Beow, son of Scyld Scefing. Healfdene founds the Scylding house (Skjoldungar), the royal house in which Danish identity has been centered (ideologically, anyway) ever since. Healfdene lived to old age, as did his son Hrothgar.
The Danes under Healfdene and Hrothgar became embroiled with the Heathobards, a tribe centered on Zealand. The center of their power was at Lejre, a site associated with pagan sacrifice. The king of the Heathobards, Frothi, was killed in the conquest. The Scyldings made Lejre their new capital. Hrothgar raised his famous mead-hall Heorot on the site, which in legend is plagued with the visits of Grendel.
Hrothgar (in Norse, Hroar) ruled with his brother Heorogar (Norse Helgi), who died before him, leaving a son Hrothulf (Hrolf Kraki), a figure as great in Danish legend as Arthur is in British tales. Hrothgar also had a sister whose marriage to Ongentheow, king of the Swedes, determined Danish policy toward the Geats, since the Swedes were attempting to expand their rule southwest at the expense of the Geats, who dwelt between the Danes and the Swedes.
Hygelac, king of the Geats, and his queen Hygd, had a son, Heardred. Hygelac was also in legend related to the young hero Beowulf, who rid Hrothgar’s hall of the menace of Grendel. When Hygelac died in a raid on Frisia c. 525, Beowulf protected the very young Heardred’s right to succeed him. When Heardred died, Beowulf is supposed to have taken the kingdom of the Geats himself; but dying without an heir, the kingdom of the Geats was then absorbed by the Swedes.
Meanwhile, Hrothgar and his queen Wealhtheow had married their daughter, Freawaru, to Ingeld son of Frothi of the Heathobards. This was supposed to reconcile the Heathobards to the Danes; however, one of Ingeld’s retainers attacked and killed a Dane in Freawaru’s service, which led to Ingeld abandoning the Danish alliance. Ingeld was killed and the Heathobard kingdom disappeared, but not before Heorot was burned to the ground in the fighting.
All of these events are touched on in the poem Beowulf. They form the historical and legendary background of the Old English people. Most of the peoples from whom the Anglo-Saxons came or with whom they had historic connections are included: the Danes, the Jutes, the Frisians, the Angles, the Heathobards, the Geats, and the Swedes.
The Angles, Frisians, Jutes, and (presumably) the Heathobards are all Ingvaeonic Geman tribes. “Ingvaeonic” can refer to dialectal relationships; all the Germanic peoples in the area at this time would have been more or less mutually intelligible to each other, but Anglo-Frisian is the source of the English language, so these peoples are particularly closely connected to each other. “Ingvaeonic” can also refer to shared religious beliefs. The western Germanic tribes were followers of Ingvi-Frey, whose fertility cult centered on the gods referred to later in Old Norse as the Vanir – Nerthus, Frey and his sister Freya. The Danes and Geats (connected to the Goths) worshiped the Aesir; Odin and Thor were their chief gods. The Norse story of the war of the Aesir and Vanir parallels the real world takeover of Ingvaeonic tribes by Proto-Norse tribes. It is notable in this connection that Hrothgar named his daughter Freawaru, a name connected to the cult of Ingvi-Frey; having taken over the cult site of Lejra and built his own stronghold on it, he was at some pains to nativize his family in Ingvaeonic terms, even before his attempted reconciliation with the Heathobards by marrying his daughter to Ingeld.