Mygeeto was a cold place with lots of neat crystals. The Muuns thought it would be a good place to hide money, so they constructed crystal mines that could double as vaults. Naturally, this meant that the planet would have to be well-defended from would-be bank robbers. When the Clone Wars broke out, The Intergalactic Banking Clan siezed all the assets stored on Mygeeto for use in the war effort. The Republic made Mygeeto one of its primary targets, but was unable to really do anything there until very late in the war. Even though the vaults were empty, the Empire kept the mining operations going, and Mygeeto remained a center of the financial industry for quite some time.
Nobody. Just crystals and money.