The T1-TANs where massive sentient AI battle machines. They fought on the side of the Stone King. The T1-TANs were said to have struck terror into the hearts of Kondo's forces. There enormous eyes enough to unnerve the most disciplined soldier.
The T1-TANs came in a variety of forms. There were walkers, fliers, siege machines etc. They were believed to have all been destroyed when Kondo released the Cargothen (the story of which is told in the Myth of the Bond)