The Viking Who Gave His Name to Wireless Technology

harald bluetooth viking technology


We all know Bluetooth is a wireless communication technology but did you know that a 10th-century Viking king inspired its name and logo? Known as Harald Blåtand Gormsen in Danish or Harald Bluetooth Gormsson in English, King Harald reigned over Denmark between around 958 to around 986.


Although his name was given to the well-known technology, the first Christian king of Denmark’s story remains largely unknown to most people. Harald Bluetooth gave Denmark and Scandinavia the impulse to join booming-medieval Europe during his reign.


Who Was Harald Bluetooth?

august thomsen gorm and thyra painting
Gorm the Old learns of the death of his son Canute, by August Thomsen, ca. 1860, via Bruun Rasmussen


In the shadows of history for centuries, Harald Bluetooth suddenly became famous when a couple of men dug up his name from the depths of Viking history and gave it to an innovative new technology. The Viking king played a fundamental role in the unification of Denmark with its neighbors (now the countries of Norway and Sweden), and he helped to Christianize Scandinavia.


The scarce information available about the first Christian king of Denmark comes from varying sources written during Harald’s reign and by later chroniclers. They certainly did not hesitate to embellish or exaggerate some of his traits, sometimes giving divergent descriptions but contributing to the Viking king’s legend.


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Harald was described as “remarkable by the force of his mind and faith” but also “deprived of wisdom” and “without great intelligence.” Several chroniclers praised the great warrior and king and wrote about the animosity between Harald and his son Sweyn Forkbeard.


As his family name Gormsson would suggest, Harald was the son of Gorm the Old, king of Denmark, and Thyra. He was probably born around 920. In 958, Harald replaced his father at the head of a vast kingdom covering today’s Denmark, parts of Norway, and Sweden.


Denmark’s First Christian King

wenzel torn¢e ansgar painting
Ansgar, by Wenzel Tornøe, ca. 1895, via Wikiart


Harald was born pagan like his predecessors, worshipping the Norse pantheon’s gods. Around 960, maybe in 963, Harald converted to Christianity, becoming Denmark’s first Christian king. It was not a novelty as Christianity had progressively spread across the region since the 9th century. Yet, the king’s conversion made the new religion durable.


Harald’s conversion was not only an act of faith but also a political decision. Otto the Great, the East Frankish king and Holy Roman Emperor in the mid-10th century, threatened to expand his territories across Danish borders. His first move was the creation of bishoprics in Denmark and Harald’s conversion helped the Danish Church maintain its independence. Harald wished to keep his people’s trust and ensured a smooth transition from paganism to Christianity by not forcing them to give up their old beliefs and traditions.


Why the Nickname Harald Bluetooth?

harald bluetooth roskilde cathedral painting detail
Detail of a portrait of Harald Bluetooth, 1565-1585, via


So why was king Harald known as “Bluetooth”? The origin behind this nickname is probably not that charming. Harald supposedly had a rotten tooth, which looked blue or black as his Danish name would suggest: Harald Blåtand Gormsen, blå meaning blue and tand tooth.


The first mention of this detail appears in the Chronicon Roskildense,  a 12th-century Danish chronicle written in Latin which describes Danish historical events, including the kingdom’s Christianization. The author used the Latin word Blatan to describe Harald without providing further details.


William of Æbelholt, a French churchman who moved to Denmark to help restore religious discipline in the diocese of Roskilde, was the first to explain King Harald’s blue tooth. In his genealogy of the Danish kings, written during the second half of the 12th century, William described Harald’s tooth as dark blue, almost black.


Yet, the origin of the tooth’s color remains unknown. Harald may have had a rotten tooth that was particularly visible. The lack of health and dental care at the time meant it was common to have bad teeth, even among royals.


Some give a less gruesome explanation for Harald’s nickname. Scandinavians are very fond of berries, a type of wild fruit widespread in northern lands. Harald may have been particularly fond of blue-colored berries, and it may have caused his teeth to blacken.


Mentions of the blue tooth only appeared two centuries after Harald’s death. During his reign, the king was undoubtedly known as Harald Gormsson: the son of Gorm. In Scandinavian tradition, people were known by their first names. They also used a patronymic made of their father’s name or, less often, of their mother’s name. The father’s or mother’s name was followed by the -(s)son/-sen suffix or -dóttir/-dotter. Eventually, it became a kind of surname, sometimes combined with an inherited family name. The mysterious origin of Harald’s nickname remains unclear. Because of its singularity, Harald and his supposed blue tooth stood the test of time and eventually became famous.


harald bluetooth roskilde cathedral painting
Portrait of Harald Bluetooth, 1565-1585, via the National Museum of Denmark


Gaining a clear impression of Harald’s general appearance is also challenging. One of the few depictions of him, a painting on one of the pillars of Roskilde cathedral, shows Harald dressed as a man from the 16th century with red stockings, a blue skirt, and golden armor. Things he would not worn in his time.


lorenz fr¢lich thyra dannebod dannevirke foundation print
Thyra Dannebod ordering the foundation of the Dannevirke, by Lorenz Frølich, 1855, via Royal Danish Library


Despite the dearth of written sources about Harald Bluetooth, the Danish king left plenty of archaeological traces of his reign. Among his landmarks, Harald established a network of round-shaped fortresses across Denmark and southern Sweden. He also modernized the Dannevirke, a fortification network in Schleswig-Holstein, in neighboring northern Germany.


The Jelling Stones complex is the most significant and precious source of information about Harald Bluetooth. Archaeologists have studied this vast carved runestone site in central Denmark since 1704.


Harald’s father, Gorm the Old, probably erected the first carved stone in memory of his wife, Thyra. Harald raised the second stone to honor his parents and to celebrate his political success. With its runic inscriptions, Harald’s stone constitutes a precious source of information about his accomplishments: the annexation of Norwegian and Swedish territories and the Christianization of the kingdom.


jelling stone harald bluetooth
The Jelling Stones, photographs by heller_dk, via flickr


Like his father before him, Harald was part of the Jelling dynasty. The Jelling dynasty, also known as the House of Knýtlinga, started with the legendary Danish king Harthacnut, father of Gorm the Old, and it counted a succession of several kings up to the death of Harthacnut (also known as Canute III) in 1042.


The Jelling dynasty’s successive kings shaped Denmark’s kingdom, making it one of the most powerful kingdoms in 11th-century Northern Europe. At its peak, its territory spread from Northern Norway to England.


Forced into Exile by His Son

s¢ren pilmark as sweyn forkbeard vikings valhalla
Søren Pilmark as Sweyn Forkbeard in the Vikings: Valhalla tv series, via Netflix


After many years of political success, and the establishment of a strong power over vast unified territories, the end of Harald Bluetooth’s reign was initiated by the revolt of his son, Sweyn. The latter, along with some unhappy aristocrats, forced the king into exile during the 980s. He settled somewhere in the southern part of the Baltic states.


Harald died shortly after being exiled. According to later sources, an archer killed the exiled king while the latter was relieving himself; what an ending for the great Viking king! Even the location of his grave remains in the dark. Sweyn most certainly contributed to the loss of information about his father’s life. It was only during modern times that Harald was rediscovered. First by the Danes, who saw in him a key figure in their national history, then by others, thanks to a new revolutionary technology named after him.


Harald Bluetooth and the Birth of Bluetooth Technology

jim kardach harald bluetooth picture
Harald Bluetooth holding a cell phone and a laptop, by Jim Kardach, via Intel Free Press, Flickr


In 1997, several big communication companies such as IBM, Intel, Ericsson, Nokia, and Toshiba developed a new technology to connect devices. Nokia and Ericsson, two Nordic enterprises, led the project.


On a windy night, in a bar in Toronto, two engineers from Intel and Ericsson who were working on the project were having a drink. They were looking for a good name to give to their new technology. During their conversation, they talked about their shared love for history. One of them mentioned a book he had just read about the Vikings, including one peculiar Viking king: Harald Bluetooth.


The engineers made a parallel between Harald Bluetooth, a unifying king, and the tool they had created to connect various devices in a unique network. One of them, Jim Kardach, created a PowerPoint to explain the name choice to his superiors. It contained a picture of a stylized Harald on a stone, holding a cellphone and a laptop.


Bluetooth became a code name for several months, yet it was supposed to be replaced by the name “RadioWire” or “PAN” (Personal Area Network). But the communication team grasped the power of the meaning behind “Bluetooth” and they kept it as the technology’s official name. Bluetooth was officially launched in 1998, and Ericsson created the first Bluetooth phone in 1999. The technology is still widely used today.


bluetooth logo origins
Bluetooth Logo origins, via Creative Bloq


Interestingly, the Bluetooth logo is also inspired by the runic alphabet, used by Germans and Scandinavians between the end of antiquity and the Middle Ages. By combining the initials of Harald Blåtand, they came up with the current logo.


As the public became increasingly interested in the Vikings and their history through comics, books, and tv shows, the rooting of the product’s name in the culture of its place of origin seems to have offered the company a competitive advantage.


Like king Harald who unified kingdoms, Bluetooth technology connects various devices. It also represents the joint effort of those leading different enterprises to enable communication between their products.