10,000 years before the events of MK3, Shao Kahn's Queen Sindel met an untimely death. We know that Kahn's Shadow Priests, led by Shang Tsung made it possible for her soul to one day be reborn - not on Outworld, but on Earthrealm. When Sindel died, her soul was bound for one of two places: The Heavens or the Netherealm. If her soul went to the Heavens, it would've been forever lost to Kahn as surely the Elder gods would not give her up to him for any reason, nor could they be forced to. However if her soul went to the Netherealm, Shinnok and Quan Chi, it's rulers, could possibly be persuaded to go along with their scheme. Therefore, as we know, Shang Tsung and company brokered a deal with Shinnok and Quan Chi (the first incarnation of the Deadly Alliance) to help Kahn in his diabolical scheme.
As a side note, Scorpion's UMK3 and MKT bios mention Kahn attempting to overtake the Netherealm (called Earth's Hell there). This hints at a possible attempted double-cross that I'll examine closer in a future article.
The scandal, then, appears when one considers why Sindel's soul descended into the Netherealm. At the time the young Queen was the victim of a horrible turn of events. She watched helplessly as the greatest warriors of her realm fell to the merciless wrath of Shao Kahn. In the end, even her great King Jerrod lost to the tyrant. Then, if that weren't enough, Kahn sapped the energies of her realm turning it into a desolate wasteland. Finally, the Emperor took Sindel's daughter as his own. Sindel must have known an incredible sadness in those days. But yet she was innocent. Surely if she died then her soul would have found rest and peace among the Elder gods.
Consider Shang Tsung's MKA bio where it mentions Tsung pledging his soul to Kahn, which was binding even beyond death. So it could be that Kahn manipulated Sindel, possibly under the influence of magic, into making some sort of vow. Then he might have orchestrated her death - possibly even staging a suicide. This ensured her soul went where he needed it to. Tucked away for 10 millennia until he needed it once more.
I always picture that the news of the young Queen's untimely death was the final blow to the will of the newly subjugated Edenian people. Undoubtedly nobody was convinced her death was of her own volition nor was it an accident. But surely the broken people of Edenia wept bitter tears as the news spread throughout the land as they came to realize their last symbol of hope was gone.