When the Illiadians came to Sancstoryl, they also brought their Ena-Technology. Said Ena-Tech was then often backwards-engineered by the ancient sancstorylian scientists, who then made it run on Magic. The Mata were the result of an experiment to create something new from the resulting Magitech. Originally just constructs of wood and/or metal running on magic, these creatures eventually developed sentience and a genuine soul. After much pressure on the ancient Sancstorylians from the Illiadians to not start a conflict over this, the Mata, even as rare as they were, were then integrated into Sancstorylian society as fully-fledged citizens. After The Great Wasting, the secret to create Mata slowly became a distant memory, becoming lost completely after an invasion of Grehel in the 11th century PW, where they still were being built for about a thousand years after the wasting, but it has since been rediscovered a few decades ago.
Many Mata are at least one or two thousand years old, with some even remembering the time before the Great Wasting. However, quite a handful were also built in the past few decades, after the rediscovery of ancient Maton-blueprints.
The creation-method for Mata makes them a type of humanoid after the acquisition of their soul, rather than a construct.