The Chinas

The following article is not intended as a political statement and should not be taken as such. Rather, it reflects a possible alternate course of history, given the differences between this scenario and the real world.
====== Humiliation Period (1954 - 2246): ======
This period is marked by the expansion and increased severity of the Chinese Civil War. At first, the Kuomintang had managed to consolidate power but this era was short and quickly devolved into a swift shift towards warlord states and anarchy as the Kuomintang's power diminished. When the Japanese returned to the Chinese mainland and continued the Sino-Japanese War, the Chinese fought valiently but in vain. Victory was gained only after massive loss and it was often undone soon after obtained. After years of conflict and skirmished, the borders stablized and remained secure. 1991 marked the end of the Great War, and the arrival of peacekeepers sent to enforce a DMZ alongside peace treatries and other events that came with a war's end.
While large scale offfensives had been rendered unachievable and an unrealistic goal, the Worker's Army continued to fight using guerilla tactics and adapting to technolgical advances. The Worker's Army was the first group of people to perform Trojan Horse attacks, where a rocket was made to mimic the enemy's rocket and sent towards their bases to wreck havoc. Often suicide missions, these trojan events were effective but lethal.
Tensions rose in 2139, after the Yunnan Autonomous Republic elected a new prime minister, who took dictatorial power for himself. While mostly interested in internal affairs, the dictator aligned his state with the Japanese to threaten the Republic of China (Southern China) with a two-front war, a civil war in one corner and a foreign invasion on the other. 
His death in 2187, allowed the Yunnan Parliament to regain power, though this briefly increased tensions, it quickly died down and pressure was eased off of the Southern Chinese State. 
====== Rebirth Period (2246 - 2309): ======
China's rebirth would come at the decline of the Japanese in both industrial and economic might. For centuries, Japanese Emperors weakened while Chinese puppet monarchs gained increased autonomy and less oversight. By 2246, Northern China beat Japan in nearly every metric, while Japan remains stronger per capita, Northern China had a larger population, military, total economy, and resource availability.
The weakened state of Japan can be seen in Korea, as the state rapidly gained great autonomy at the cost of a massive decline in the Japanese army and navy. The case of Korea would see the Chinese grow more daring. With a recent secret agreement between the South Chinese prime minister, and the North Chinese Monarch, China seems to be destined to reunite once again. 
"The empire, long divided, must unite; long united, must divide. Thus it has ever been." - Luo Guanzhong