Prior to her posting aboard Enterprise NX-01 in 2151, T'Pol had observed a demonstration of a device similar to a replicator on a Tarkalean vessel. She stated, "It was capable of replicating almost any inanimate object." (ENT: "Dead Stop")
Doctor Phlox was able to initially assist the Tarkaleans; however, he discovered that the Borg nanoprobes had infiltrated their autonomic systems and that their renal glands were replaced with cybernetic devices. The Tarkaleans eventually succumbed to the Borg and one of the Tarkaleans attacked and injected Phlox with nanoprobes. The Tarkaleans later escaped sickbay and attempted to modify the systems of Enterprise, forcing Captain Archer to eject the two into space. (ENT: "Regeneration")
The Tarkaleans were well known for their special blend of Tarkalean tea. (DS9: "Past Prologue", "Cardassians", "The Wire", "Distant Voices", "Hippocratic Oath", "Let He Who Is Without Sin...", "Trials and Tribble-ations", "What You Leave Behind")
In 2372, for a shipment of Karemman fleece imported from the Karemma, the Ferengi imposed a six percent tariff, claiming that the tax was added to help offset the "lost income of Tarkalean sheep herders." (DS9: "Starship Down")
The Tarkaleans, though mentioned often in Star Trek, made their first and only appearance in "Regeneration".
"Tarkalean" was incorrectly spelled in the script for Starship Down as "Tarkalian", but it is believed to be a simple typographical error. A similar error was made in the script for "Hippocratic Oath" where the spelling "Tarkalian" appeared in the pronunciation guide, but the spelling was later corrected to "Tarkalean" later on in the script. Another similar situation was in the script of "Regeneration", in which all but one reference to the species was spelt "Tarkalean", the exception again spelt "Tarkalian".