Original:  From 1949 to 1987, the Kuomintang ruled Taiwan under martial law hostile to the Communist mainland  , before Chiang Ching-kuo  lifted authoritarian restrictions and initiated democratic reforms in the late 1980s.
Revised:  From 1949 to 1987, the Kuomintang ruled Taiwan under martial law hostile to the Communist mainland for nearly 40 years , before Chiang Ching-kuo lifted authoritarian restrictions and initiated democratic reforms in the late 1980s.
Edit intent: meaning-changed