T'Rillan was a planet located somewhere in the space of the galaxy's Alpha or Beta Quadrants, in orbit of the T'Rill star system, at coordinates 3.26N 4.05E.

In the 23rd century, T'Rillan was home to a Vulcan agricultural colony. By reference stardate 2/2306.01, the world had a population of 12.2 billion individuals, mostly Vulcan, and the government was a full-status colonial member of the Federation. (FASA RPG module: The Federation)