The promised Horde section of WOW power leveling guide which are Implemented from various posts by Horde players have contributed. Some of these spots which can help you easily power leveling were also taken from Ratama of Nurfed.

14-16: Pirates south of Ratchet (Barrens)
16-19: Various wildlife, especially cats, in Barrens. Note that if you're using a dagger crit build, then exp for this is insane.
19-22: Bramblescar (Barrens) on lizards and quillboars. Unless you're doing leatherworking, just leave the lizards alone.
22-24: Tarren Mill (Hillsbrad) on bears and spiders. Dagger crit chain heaven.
24-26: Across the road from Tarren Mill on tougher bears and cats. Dagger crit chain heaven.
26-28: Spiders/Bears in back of Syndicate tower (Hillsbrad)
28-30: Cats and Spiders around Nethander Stead (Hillsbrad)
30-32: Harpies inside cave (Thousand Needles) NE of Brackenwall (2 min run there)- Raptor den
36-37 raptors there - lots of them
40-42 Skeletons in Desolace. They're about the only squishies I could find to grind on. It's part of an Alliance quest, so the usual PvP warnings apply.
42-45 Jungle Stalkers in SV. The loot drop isn't nearly as good as the Lashtails, but they're as squishy as ever. Also, they don't seem to have the knockdown attack that the lashtails do. Virtually no one kills these guys on my server, and they're easily chainable.

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