'The PR guys hated the name': The 1,000-year-old story behind Bluetooth

A pair of ancient runestones in Jelling tell the story of the Viking king who shaped Denmark – and inspired the name Bluetooth.

If you've ever wirelessly connected your phone to your headphones or laptop, you're probably already familiar with the name Bluetooth. But while the technology is modern, the story behind the name stretches back more than 1,000 years to a Viking king whose legacy can still be seen in Jelling, a small Danish town about 250km (155 miles) west of Copenhagen.

Here, two ancient runestones tell the story of his reign – and offer the first clue to how his unusual nickname became attached to one of the world's most widely used technologies.

The king was Harald Gormsson, who ruled Denmark in the 10th Century. His nickname was Bluetooth – Blátǫnn in Old Norse – first documented 150 years after his death and believed to be a nod to a "blue" or rotted tooth.

One of Harald's most consequential achievements was Denmark's conversion to Christianity, thought to have taken place around 965. The larger of Jelling's two runestones, commissioned by Harald, declares that he "won himself all of Denmark and Norway and made the Danes Christian" and bears one of the earliest depictions of Christ in Scandinavia.

Until then, much of northern Europe was divided into smaller territories ruled by chieftains. Christianity gave Harald a way to consolidate power, strengthen Denmark's ties with Christian Europe and help unify the emerging state.

"It is the nation building of Denmark after 200 years of the Viking age, where the Northerners had a pretty steep learning curve," said Adam Bak, curator at the Kongernes Jelling Experience Center and Museum. "They get well-versed in different forms of politics in Europe, of what Christianity can do for them, and the centralisation of power in a state."

Harald's story is written into the landscape at Jelling. His father, Gorm, commissioned the smaller and older of the town's two runestones in memory of his wife, Thyra. It is believed to contain the first written use of the name "Denmark" within the country.

"We call it Denmark's birth certificate," said Anne Havgaard Mikkelsen, a resident of nearby Vejle. Jelling, then, is its birthplace.

Though it has only 4,000 residents today, it was the seat of power in Harald Bluetooth's time. Originally a pagan burial site, Jelling became a place where pagan and Christian traditions overlapped during Harald's reign.

Today, white posts mark the palisade that once enclosed the Jelling monuments, while hundreds of markers trace the outline of a vast ship-shaped layout, possibly dedicated to Thyra. Two burial mounds and a Christian church complete a landscape that Bak says is less about "bold Viking warriors and Thor and Odin" than about "politics and transition, the change from something older to something new". 

In 1994, the Jelling mounds, runic stones and church became Denmark's first Unesco World Heritage site. At nearby Kongernes Jelling visitor centre, interactive exhibits trace the transition between Viking beliefs and Christianity, while the two runestones – Denmark's baptismal stone and birth certificate – stand protected behind glass.

More than 1,000 years later, Harald's reputation as a unifier would give his name an unexpected second life.

In the late 1990s, engineers from companies including Toshiba, IBM, Nokia, Intel, and Ericsson were developing a new technology that could connect devices across different brands. They needed a codename.

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Jim Kardach, an American Intel engineer, was collaborating with Swedish engineers when the conversation turned to Vikings. Intrigued, he immersed himself in a book about the history (which is on display at Kongernes Jelling) and became fascinated with the king who united Denmark and Norway, just like this new technology might unite different devices. 

The code name leaked before the official press release was written, and the rest is tech history.

"The PR guys hated the name because they associated 'Bluetooth' with bad tooth hygiene," said Bak. "They were very concerned about it and had all kinds of different names that were better at explaining what the product was, but were way more boring. Bluetooth blew up because it was so distinct a name."

Its rune-inspired logo also helped its staying power. The ubiquitous symbol combines the Norse rune for "H" and "B" in honour of Harald Bluetooth.

On the 25th anniversary of the technology in 2023, Kardach and other founders travelled to Kongernes Jelling to lightheartedly "apologise" for using Harald's name without permission. The museum in turn accepted the apology and gave them permission keep using it for the next 1,000 years.

"Harald loved showing off," said Bak. "I think he would be very happy to know that billions of people say his name on a daily basis today."

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