Tagus III
Tagus III was the inhabited third planet in the Tagus system, in the Beta Quadrant. This was the homeworld of the Taguans. 

Civilization existed on the planet for over two billion years and it was therefore one of the most important archeological sites in the galaxy. Up until 2367, 947 archeological expeditions had been conducted, with 74 of them revealing findings of major importance, the first one 22,000 years prior. A significant number of these excavations had been conducted by Vulcans through the Vulcan Science Academy. Other expeditions had been conducted by the American Continent Institute, the University of Alpha Centauri, the University of Hawaii, the University of Betazed, and the Memory Alpha Cultural Institute. Y'zjete H'ieh City was one target of such expeditions.

The history of the planet was divided into different periods, such as Arnold Era, Post-Ramirez Era, Pre-Neskoromny Era, and Sepulveda Period.

The Taguans sealed off the ruins to foreign visitors in the 23rd century, but the ruins were still the focus of much interest. In 2367, the annual symposium of the Federation Archaeology Council was held in orbit of Tagus III on board the . ()

Appendices

Background information 
This planet's quadrant of origin is inferred based on the position of its star system as seen in the star chart appearing in the  episode .

Apocrypha 
In the  Q-Space, Q takes Captain Jean-Luc Picard into Tagus III's distant past to witness a prominent local ceremony of the era, where the  – the previous sentient inhabitants of Tagus, with the Taguans of the present apparently a later evolution of life on their world – perform a ceremony where a group glide for over two days and proceed to sky-dive into a ring of fire to evade man-eating sea snakes, Q noting that he enjoyed witnessing the rite in his youth as it reflected how lower beings were unafraid to take chances and refused to accept limitations in favor of doing something with their lives.

External link 
 

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