Sakethan

The Sakethans were a group of Vulcan dissidents who left Vulcan many centuries ago, and established themselves on several planets including Calder II and New T'Karath.

On the planets they visited they constructed burial mounds, where they interred many of their dead, or priceless artifacts. By the 24th century, these burial mounds were all that remained of the Sakethans. (TNG episode: "Gambit, Part I"; novel: Glass Empires: "The Worst of Both Worlds").