Tandar Prime was the main planet in the Tandar planetary system. This was an important planet in the Tandar sector, home to the Tandaran race and center of their territory. As of 2152, it was governed by the Tandaran Central Magistrate.
One of the provinces of Tandar Prime was Querella Province. Prior to 2144, Danik worked as director of an engineering institute there before being taken into custody for being Suliban. Danik's grandfather was one of the many nomadic Suliban looking for a new home after the Suliban homeworld was destroyed, and he chose to move his family to Tandar Prime.
The capital city of Tandar Prime was quite impressive. When Colonel Grat sent Enterprise to Tandar, he suggested that he would try to pull some strings for a special ambassador to give them a private tour. (ENT: "Detained")