World of Warcraft is very old, by videogame standards. It was released in 2004. And about every two years, Blizzard releases a new expansion to update the game. Typically expansions don't really replace content, but it does displace it, and changes to mechanics and player abilities are indeed permanent and "retroactive". And in 2010, the Cataclysm expansion DID actually replace the old content from the release game.
Swim Speed Potions (used especially at lvl 37 for Faldir's Cove in Arathi Highlands and lvl 57 in WPL). Try to get multiple stacks of these. I also recommend keeping a stack of these always in your bags. You will frequently pass rivers and lakes and can use these potions to pass them faster through out the guide. Please note that these potions do not stack with Druid's Aquatic Form and Glyph of Aquatic Form.
Kurzen's Compound (marked BLUE on the map) - Colonel Kurzen was once a very talented Stormwind Officer. He was sent with an expedition to the Jungles of Stranglethorn, where he fell victim to Mai'Zoth, a powerful Ogre Mage and his foul magic. Majority of Colonel's troops are still loyal to him and provide Players with some valuable Loot. In this spot, you will encounter Kurzen Jungle Fighters, Kurzen Medicine Men, Kurzen Wranglers, and Kurzen Commandos. These Humanoids drop a lot of Silk Cloth (that can be generally turned into Bandages and Vendored), valuable Wool Cloth (the main source of Gold from this spot, check the AH prices), Fadeleaf (Medicine Men), Liferoot (Medicine Men), 12 Slot Bags (Commandos), Vendor Trash Items, and some Pocket Money. This spot is especially good for Rogues, as the ability to Pickpocket mobs will increase profits by a noticeable margin. Recommended Level - 34+ (36+ to be extra safe, as Humanoid mobs can be problematic because they tend to run away on low health and pull additional enemies).