Located due south of Duskwood is the tropical jungle-like Stranglethorn Vale.
This is an extremely large zone, and can usually take a player through about 7-8 levels worth of quests. The northern part of the zone features the Nesingwary Expedition, a hunting party that offers chain quests for both factions that players tackle hunts of gradually-stronger animals, until they are tasked with taking on an elite tiger or panther. This is one of the most PvP heavy areas in the entire game, as you will almost always find high level players killing lower-leveled players trying to quest.
The Alliance comes upon a camp of soldiers who have recently deserted the crazed Colonel Kurzen (corrupted by some nearby ogres), in the northern part of the zone. They offer quests that have you deal venture into the insane leader's territory and end the threat.