The Vikings are known the world over for their travels. They hail from lands such as Denmark, Norway, Finland, Sweden, and others, each having its own native language. But Vikings visited and traded with many lands, including England.
Since the Vikings were so well travelled, and England was one of the first places they invaded and plundered, it would seem that at some point they would have learned the English language. The Viking Age, however, was between 800 AD and 1066 AD, and English, as we know it, did not exist. Vikings did not, therefore, speak English.
Languages tend to change over time. There are some benchmarks of the development of the English language in literature. The most prominent may be the King James Bible. It was translated and published in 1611, and written just after the period that gave us “Middle English.” Many today do not enjoy reading the King James version, as the language, while understandable, is lofty, and different from modern, colloquial English.
Before that, Middle English gives us documents that are nearly unreadable for most modern English-speaking people. Geoffery Chaucer’s writings can be read, but hardly understood at all, but for a few words that did carry over..
Going further back to the period of the Vikings, we have “Beowulf”, an ancient English poem, a document which none but those who study “Old English” can actually read and understand. This would have been from the later Viking period, when Danes were speaking Old English.
English is a “Germanic” language, meaning it derives from the same family of languages as does German. It has been heavily influenced by other European languages, especially French, and by the ancient, “classical” language, Latin, the language of the Church. But, it was also influenced by “Old Norse”, the original language of the Vikings.
Old Norse is also a Germanic language. Several other languages that exist today and are widely spoken are also Germanic in origin. But, there were enough differences between Old English and Old Norse to make them completely different languages, and not simply Germanic dialects.
The Danes frequently invaded England. They started their invasions in the very early ninth century. At that time, the language was Old English, and there were four dialects: Northumbrian, Mercian, Kentish, and West Saxon.
Northumbrian was spoken in northern England and southern Scotland. Mercian was spoken in central England. Kentish was the dialect of the southeast, and West Saxon of the southwest.
The Danes first invaded Northumbria. They did not speak that Old English dialect when they arrived, but likely found it easy to learn, as it was indeed a Germanic language, as was Old Norse.
The Danes, however, eventually settled down just south of Northumbria, and became part of society. They actually ruled much of the Northumbrian and Mercian territories, and they even had Danish Kings there between 1014 and 1042; During their time in Northern and Central England, they created what is known as “The Danelaw”, a body of laws they imposed on the English peoples they ruled.
Since they took up the Old English Language and then began to rule the people, their Old Norse influenced the Old English heavily, because of the exertion of their ways over that part of English society. Words like “wrong”, and “skull”, and berserk came to Modern English all the way from Old Norse, via Old English.
The Normans invaded England from northern France in 1066 AD, ending the Viking Age. They brought with them their own version of French, “Old Norman French”, and out of that, along with Old English that had been influenced by Old Norse, developed the “Anglo-Norman” dialect.
After that, the Middle English of the Chaucer era emerged. Old Norse, the language of the Danes, was no longer spoken in England. Neither was Old English.
The English that was spoken then would be unrecognizable to the modern English speaker. A Norseman who might have wandered into Chaucer’s England would first have to learn a very new language in order to communicate.
The Vikings, therefore, over time and due to their travels, spoke many languages. They carried with them Old East Norse, Old West Norse, and Old Gutnish, depending on where the particular Viking Horde was from.