Best I've gotten was about 32,000 from the sea, bandit camp that had something like 14 bandits, was hard to tell as they ran off the screen and had to rely on auto attacks for the last few. If you're in deeper region game code looks to add 20-60% more units, normal bandit camp has normally up to 8 bandits and 2 leaders, so that means up to 13 bandits and 3 leaders, 16 total. If you got lucky and succeeded the loot roll on all 16 bandits, you'd get aa 65,536x gold multiplier in total. Basically get in the 100's of thousands. Far as I can tell region doesn't matter, marsh would be harder to win, but no different in reward? Higher level slaves to capture though.