When Bluetooth technology was being developed in 1996, its creators struggled with naming the technology. As YouTuber Tom Scott explains in his latest video, their final choice came from an unusual place: Viking history.

In Jelling, Denmark—the country’s ancient capital—there is a set of thousand-year-old runic stones known as the Jelling Stones. The biggest of these, called the “Danish Birth Certificate,” was built by King Harald Bluetooth around 964 CE, honoring the founding of Denmark (and using that name for the first time) and the country’s conversion to Christianity.

During the early phases of the technology’s development, Intel engineer Jim Kardach called the project “Bluetooth,” a code name that wasn’t supposed to last beyond when the project went public. Harald Bluetooth was famous for uniting Denmark, he said, and the short-distance radio wave technology would unite cell phones and computers. He had just seen a picture of Harald Bluetooth’s runic stone in a book on the Vikings, after a Swedish friend tipped him off to the story.

The official name of the technology, for a while, was going to be either RadioWire or PAN (personal area networking). PAN won out in a board meeting vote, but because it would have been impossible to trademark, Bluetooth stuck in the end. Luckily, it made for a great logo, too. That bright blue squiggle used as the Bluetooth logo comes from the runes ᚼ and ᛒ. Or, in the Roman alphabet, H.B.

[h/t Digg]