how are there no tribes or clans of people on Gran Pulse??
Storywise, because after the last war they killed each other off fighting for the necessary resources to survive.

HUNTS AND MARKS ARE NOT SIDEQUESTS!!!! we are doing the EXACT same thing that we've been doing the entire game.. killing monsters!!! lets see something, ANYTHING else to break up the action. chocobo racing, card games, blitzball, chocobo hot and cold were all good ideas but hunts and marks SUCK.
In FFXII, the Marks were the only things that kept me going through the game. I progressed the storyline to level up so I could kill the next one. I didn't even do most of them in FFXIII though. I hated the FFIX card game but loved the FFVIII one. Blitzball was alright but I pretty much hate all the chocobo sidequests from each game they're in.