I had begun to work on it, but currently my idea run somewhere else so i have abandoned about goblins. Nonetheless:
Goblins, hobgoblins, bugbears, plus a few similar races (including an homebrew "ogrelin") are all variations of the same root race. Then, I find a poor and boring idea that these races are unrelated and found in scattered primitive tribes of their own living in ruins or cavers. In my homebrew I took idea from some Internet stuff (13 Kingdoms I believe) and created a militaristic Empire.
As such, goblinoids are organized and "civilized" although they are LE and aggressive. They live in a feudal society, in a vast empire of their own. Their society is divinded into castes. The ruling castes are hobgoblins, generally warriors and priests who oversee a much larger population of goblins serfs, slaves, and lowly commoners. Bugbears are unruly barbarians living in the wild highlands of the north (counterpart of Scottish highlanders in 13th century England); they usually cause trouble, yet some individual become gladiators, bodyguards, and what not.
Goblinoids are militaristic minded. As such a few new character classes of warriors were created just for them (Ironguard, Brawler, etc.) to replace some classes that don't exist in their society and to add some flavor. These classes are not available to non-goblinoids.
Note that all of these goblinoids are not 1st level warrior NPC class weaklings. Goblins are 1st level weakling when they are starved beaten slaves only. Many goblins are 3rd level thieves; many hobgoblins are 3rd level and above fighters, ironguards, etc. This is a society of disciplined soldiers and could well take over the whole humans - dwarves - elven lands (to the West) if they dared to. However, they must constantly fight against horrors from the East, so are too much occuppied to conquer humans and other humanoids.
Lastly, as a measure of exotism, hobgoblins of this militaristic empire have a culture outwardly looking and sounding like medieval Russia (Margrave, Boyar, etc.); just there is no Orthodox Christianity

.