Arathi Basin

Arathi Basin hosts a 15 vs. 15 player battle over resources which either side desperately needs to fuel the warfront.

You can join the battle starting at level 20 (brackets of 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, and 80) to assist either the League of Arathor (Alliance) or the Forsaken Defilers (Horde). Constant fast paced battles are the main draw to this excellent and quick game. The one thing to note is that it’s best you wait until the higher level range of each bracket before joining most battlegrounds, as you will be a liability to your team if you, for example, are a level 40 in the 40-49 bracket. You really should be at least at the mid-point for your current tier as you will survive longer and contribute more to your team as a result.

the full guide is here: http://www.tentonhammer.com/node/26426