By the 23rd century, Tondusians used transporter technology for travel between cities. Their society was overseen by a government led by a premier, who was served by a chief of staff and chamberlain. Their space service included a fleet of Tondusian strike craft. They were a peace-loving people.
In 2267, the Tondusian capital city was occupied by forces from the Romulan Empire. They locked all government officials in prisons with their families to force compliance from the rest of the population.
With Romulans securely controlling the police and space service, imposters resembling the Tondusian leaders warmly welcomed a diplomatic delegation from the Federation starship USS Enterprise. The landing party was captured, but a strike force led by Montgomery Scott rescued them, captured the Romulans, and freed all of the imprisoned Tondusians. (TOS comic: "The Marshall Plan")