Parracas seem to communicate only via telepathy. Though Vulcans were receptive to such contact from an individual, Humans were not. However, a communal telepathic broadcast was strong enough to be detected by a starship from a distance of millions of kilometers as audio signals.
By the 23rd century, the Parracas appeared to be advancing beyond a tribal stage of development. They had invented the wheel and built a small village on the side of Biluddin mountain. They domesticated animals such as the Parraca beast, built wheeled carts, and were generally a peaceful people. They worshipped the mountain volcano as a god of peace.
For centuries they had an uneasy relationship was their more aggressive neighbors, the Turracas, who threatened to wipe them out. In the 2260s, Parracas used spears and shields for defense. Their priestess was Maracu.
In 2266, James T. Kirk and Spock made first contact with a group of Parracas who were praying to the mountain. The Parraca heeded their warnings that the volcano would soon erupt and evacuated their village. (TOS comic: "The Gods Have Come!")