The goblin races we now call Cyrimbl and Skratta were once a single unified race.
It is widely misapprehended among even our finest scholars that differences between the two were due entirely to the Cyrimbl's enlightenment at the hands of the gnomes of Marthen Row. This is not so, and betrays an unfortunate gnomish superiority that mars much of our scholarship concerning the lower races.
In fact, the goblin schism occurred a few years prior to the Cyrimbl arrival in Marthen Row, the results of decades-perhaps centuries-old cultural divergence within the race. Though it cannot be disputed that the Cyrimbl owe most, if not all, of their grasp of the scientific method, literacy, and history to their time in Marthen Row, it was the development of a greater intelligence and civility that had led them to split from their more brutish cousins.
As for the gnomes of Marthen Row, this act of charity was to be their unmaking. It took the less civilized Skratta several decades to find what became of the departed Cyrimbl, but track them down they did. It is unclear if their tireless search was driven more by vengeance or the desire to reunite the race.
Marten Row was razed in the Skratta attack and no gnome was known to survive. The Cyrimbl, however, were able to escape in nearly full numbers, taking with them all they'd learned from our gnomish forebears along with, it is believed, a few gnomish relics of great historical value.
The Cyrimbl then fled to Thousand Eye Gorge, a dank and unwelcoming swamp, where they founded Marthenshire and laid the foundations for a new realm. There they fostered the skills they learned from their benefactors and evolved into the exacting, inquisitive, and (dare I say) learned race we know them to be today.
Despite their race's flowering in Marthenshire, the threat of a new Skratta invasion looms large in the Cyrimbl mind, though it is widely known that the Skratta have since occupied themselves with other pursuits.