Taris was one of those planets that was covered by cities. It even had a scary undercity filled with hobos, scum, and zombies. Taris was important around the time of the Mandalorian Wars, when it was filled with rich Humans. When the Jedi Civil War broke out, Taris became a key defensive outpost against Darth Malak's Sith forces. The Sith took the planet, then bombarded it in an attempt to kill Bastila Shan. After that, the planet was pretty worhtless, and it was pretty much ignored.