In 1358, the Sakya viceregal regime installed by the Mongols in Tibet was overthrown in a rebellion by the Phagmodru myriarch Tai Situ Changchub Gyaltsen (1302–1364). The Mongol Yuan court was forced to accept him as the new viceroy, and Changchub Gyaltsen and his successors, the Phagmodrupa Dynasty, gained de facto rule over Tibet.
What year was the Sakya viceregal regime eradicated?  (If the question is unanswerable, say "unanswerable")
1358