The wave of migration around 450 CE was from Angles, Saxons and Jutes. “Vikings” were men from some of these tribes that chose to live by raiding for silver and slaves. Migration for permanent settlement took over in the early 800s and York became the capital. Beowulf is a classic that has come down to us in West Saxon, but it appears to be a Danish oral history.

Vikings
The word means ‘raider’ rather than describing an ethnic group. These raiders aimed to acquire silver, either by pillage or by enslaving. The siege of Dumbarton was unusual and strategic in removing Alt Clut as a sea power. It caused the decline of Welsh speakers; those who escaped enslavement retreated to the smaller kingdom of Strathclyde which persisted till about 1100. Picts spoke a Celtic language close to Welsh. They disappeared from history, probably by retreating inland away from Viking raids on the coast, and merging with Gaels.
Scandinavian languages
Swedish is only as difficult as Dutch or German for a speaker of UK English. See if you can guess the meaning of some titles from the Wallander TV series: “Dödsängeln”, “Skulden”, “Luftslottet”.
Modern Danish has moved on from the 9th century version that the Icelandic settlers spoke. Although Danes can understand Swedish and Norwegian well, their elision makes it hard to be understood. Ladefoged, the name of the phonetics lecturer born in Surrey is pronounced this way: [ˈlɛːðəˌfoːð̩]
The Icelandic language is the most conservative of the Scandinavian group. Icelandic and the dialect of the English Lake District have several hundred words in common. They were settled around 800 CE by men from what is now western Norway. The women who settled Iceland were “British”.

Danish was more “conservative” than Old English in keeping the /g/ and /g/ sounds. Eventually OE borrowed the Danish, so we had same word twice!

The Danelaw
After years of war a peace treaty was agreed with Guthrum, who converted to Christianity with Alfred as his sponsor. It defined the Danish area north and east of Watling street. Place names still reflect this division of England.

When England was part of Denmark

Wayland the Smith
This story was known widely in Germanic tribes, but is more typical of North Germanic than West Germanic. You can probably guess some of the words in this excerpt from this version of Wayland in the Völundarkviða.
Bræðr váru þrír, synir Finnakonungs. Hét einn Slagfiðr, annarr Egill, þriði Völundr.
Níðuðr hét konungr í Svíþjóð. Hann átti tvá sonu ok eina dóttur. Hon hét Böðvildr.
The most substantial version is the Völundarkviða, an old Norse poem preserved in the Icelandic Edda. The language is Old Norse, but shows signs of having been written among Danes in England. It describes three brothers and their opponent, the king of Sweden. Here are the opening sentences of Völundarkviða: Níðuðr hét konungr í Svíþjóð. Hann átti tvá sonu ok eina dóttur. Hon hét Böðvildr. Bræðr váru þrír, synir Finnakonungs. Hét einn Slagfiðr, annarr Egill, þriði Völundr. Þeir skriðu ok veiddu dýr.
Glossary
konungur nearly the same as German
hét ‘is called’
Svíþjóð now written Sverige
tvo sonu . . . numbers and kin are strongly conserved from PIE
bræður same as biradari in Urdu; the 4th sentence is about a different family
Böðvildur female name meaning ‘battle fighter’
Þeir skriðu . . . (too difficult) ‘they crawled and hunted animals’
The Franks casket shows the story in carvings. (The right hand panel is the Christian story of the magi.) Wayland stands at the extreme left in the forge. He is held as a slave by King Niðhad, who has hamstringed him. Below the forge is the headless body of Niðhad’s son, whom Wayland has killed, making a goblet from his skull. The head is probably the object held in the tongs in Wayland’s hand. With his other hand Wayland offers the goblet, containing drugged beer, to Beaduhild, Niðhad’s daughter, whom he then rapes when she is unconscious. Another female figure is shown in the centre; perhaps Wayland’s helper, or Beaduhild again. At right may be Wayland’s brother catching birds; he makes wings from their feathers, with which he is able to escape. The runic inscription around the edge says:
ᚷᚪ: ᛋᚱᛁᚳᚷᚱᚩᚱᚾᚦᚫᚱᚻᛖᚩᚾᚷᚱᛖᚢᛏᚷᛁᛋᚹᚩᛗ | ᚻᚱᚩᚾᚫᛋᛒᚪᚾ

Bothvild is said to weep at Weland’s departure, and Weland insists to Nithuthr that Bothvild is his bride and should not be killed, so it is unclear whether he has had sex with her revenge or love. Finally, Weland, most cunning of smiths, fashions wings and so flies away in spite of his infirmity.
He and his two brothers came upon three swan-maidens on a lake’s shore, and loved them, and lived with them happily for seven years, but then the swan-maidens flew away again. His brothers left, but Weland stayed on the spot, and turned to smithing, and made beautiful gold rings against his wife’s return. King Nithuthr hears of this, steals one of the rings, takes him captive, hamstrings him to keep him prisoner, and keeps him on an offshore island and forces him to make pretty things. Weland takes his revenge by killing Nithuthr’s two sons, cutting off their heads for silver bowls, cutting out their eyes for gemstones, cutting out their teeth for brooches, and presenting these to Nithuthr and his wife. Weland also gets Nithuthr’s daughter Bothvild (Beadohild) with child, though.