The Vindolanda tablets are fragments of wooden leaf-tablets with writing in carbon-based ink. They were found at Vindolanda in northern England. The tablets date from the first and second centuries AD, which makes them roughly contemporary with Hadrian's Wall, which is near Vindolanda. The tablets contain messages to and from members of the garrison of Vindolanda, their families, and their slaves. Similar records on papyrus were known from elsewhere in the Roman Empire, but wooden tablets had not been recovered until archaeologist Robin Birley discovered them at Vindolanda in 1973. Pages have since been found at Carlisle in Cumbria, and continue to be found at Vindolanda.