Viking and Norman words
The basic nature of the borrowings, affecting language at every level, suggest that these words entered English gradually. This would be partly because of their similarity with already existent English words, and also because using the Scandinavian words would help eliminate any confusion when speaking.
This type of word borrowing is quite unlike that seen after the Norman Conquest, when the conquerors imposed their own language at the top levels of society. The native English continued to speak their own language, but gradually French words were used for new ideas, concepts and activities. French was regarded as the language of the élite, and this meant that those conscious of status tried to use French to appear more prestigious.
'This type of influence from other languages is partly why there are so many words for the same things in Modern English ...'
Thousands of French words entered the language in the medieval period. they appear in contexts to do with administration ('prison', 'castle', 'challenge'), government ('chancellor', 'court', 'royal'), religion ('grace', 'psalter', 'festival'), learning ('obedience', patience', 'authority'), and prestigious or élite activities ('tournament', 'courtesy', 'romance').
The influence of the French aristocratic language can be illustrated by the situation where the Anglo-Saxon cook in the kitchen of a French lord prepares the pig, the cow or the sheep - but when the dishes are taken upstairs they become pork, beef and mutton. This type of influence from other languages is partly why there are so many words for the same things in Modern English. 'Regal' is French in origin, 'kingly' is English. 'Paternal' is a Latin loan, 'fatherly' is English. 'Courteous' is French, 'friendly' is original English. It's clear that English has been greatly expanded by a large number of loanwords throughout the centuries.