I should tell you first that the men of ancient times were not as the men of now. We have come to accept duplicity in our fellows, and we know to prepare for dishonesty; yet the ancient ones were faithful.
They gave generously to their neighbors in need, and built structures of grandeur honoring gods far more numerous and powerful than those we worship now. Corruption was rare. So when a man of power did fall to malfeasance, the whole of the people were vulnerable, and it upset all of society.
There was one such man, Ksaran. Alone among the leaders of ancient Qalia, Ksaran commanded his servants to slay one another before him, else he would slay them in turn for disobedience. The people, powerless by their own trust-dependent measures, knelt before him and wept stinging tears. And Ksaran called them rats.
He merely chuckled when jewel-robed nobles tried to convince him to stop taking slaves of their people. Instead of stopping Ksaran dispatched his sentries upon the wellborn, who tried to scamper away before their deaths. To Ksaran, they were nothing but rats.
Merchants, wealthy beyond measure, came to his court to offer him rare spices in an attempt to calm his abominable nature, but he would have them burned alive with magic, and he would laugh that they screamed like rats.
The gods frowned upon Ksaran. They gnashed their teeth, for death would be too quick for this degenerate man. What wrath could they smite him with? What damnation could be to make him pay sufficiently for his horrific deeds?
Theindal, the Prince of Beauty, arrived at the answer. "He should become what he calls his subjects." the deity said, "he shall become a rat, and so too shall his closest circle, and they shall be cursed with the rat's form for all eternity."
Theindal made it so. And thus, the race of rat men, the Ksaravi, were born.