About the Andaria Campaign Setting (The Test of Time Supplement)
From D&D Wiki
This campaign setting was created to give a few specific races a chance to flourish, like the Lizardfolk, Merfolk and strictly lawful Orc. Furthermore I had an idea about a cosmology where plane travel is very easy but limited in it's variability to travel anywhere, I wanted plane travel to be excited and construct the cosmology so that you always have to travel to at least 1 plane before yo can go to the next.
Secondly I wanted a cosmology where times are hard, great wars are fought on the material plane and since all the important races (except the humans) have there own home plane it's hard to completely conquer them. And so the humans are caught between the endless wars between good and evil, law and chaos. The humans have a very special role in the test of time, they are the youngest race and such have been caught between the fights of the "older races" since there race where still mindless monkeys. Because of this unique heritage most humans do not trust "outsiders" and the fact that the material plane is the only plane not covert in portals (from military and economic viewpoint this has always been a great loss for the human race).
But enough of the "young ones" the greatest influence in this multi-verse are the older races, as the endless wars between the positive and negative planes rage across the planes. No one is guiltless in these wars, since everything is forced to take a side or be swept away in the tide of battle. From fisherman in The Windy Isles to Orc religious zealot for The Wasteland.