The destruction of Jurchen policies in the early Joseon period began with King Taejong

It would have been one thing if he had broken off relations and handled it well, but Taejong only started trouble.
He couldn't clean up the messes and struggled just to maintain the status quo.
Since there was no money for such military actions, he implemented policies like using "Jeohwa" (paper money) to absorb actual assets,
effectively telling creditors to "go ahead and sue me" (insolvency policy).
Fortunately, his successor was Sejong, who managed internal affairs well and pioneered the Four Counties and Six Garrisons,
but because it was a project that consumed massive amounts of the budget, tax revenue slowly melted away.
After Sejo ascended the throne, he boldly turned the money-draining Four Counties into "Pyesagun" (abandoned military districts),
and thanks to preemptive strikes against the Jurchens to eliminate future enemies, the system managed to keep running.