There is some debate on where tablet weaving began, but a partial loom was found at a burial site in Norway on the Viking ship, the Oseberg. It dates to around 850 AD.
5-minute video that gives you a great idea of tablet weaving. Gosh, he's good!
At the time of my initial research (15 years ago) internet research was not what it is today, much less You Tube tutorials, so I learned to tablet weave via this book, Card Weaving. It taught me all I needed to know about building my little loom, how to make my "tablets", how to read a pattern, and even how to create my own designs.