As far as I know, China once invaded Vietnam during Han Dynasty, the general that led the Chinese army was named Ma Yuan. In 1979 Chinese army also entered Vietnam.
Germany was going on with the holocaust and japan was invading china it all escalated when Germany invaded Poland and then WW2 officially started.
The Crusades.
The Reign of Terror was a response to the instability in France. No is was not led by invaders.
Joan of Arc
Genghis Khan
In 1368, Toghun Temur was the Mongol emperor in China. There was internal rebellion. Zhu Yuanzhang expanded his rule to Guangzhou. He invaded Beijing, the Mongol capital. In 1387, he completely freed China from the Mongol rule and founded a new dynasty called 'the Ming'
The mongols were known as the Golden Horde
Fujian
Germany invaded Poland and Japan invaded China.
Mao led the Red Chinese armies and Chang Kai Shek led the Nationalist Chinese Armies during the Communist Chinese Revolution of 1949.
The Axis invaded Poland Ethopia and China
the forceful unification of Mongol tribes by Termujin the kidnapping of Termujin's wife by a Mongol tribe the payment of tributes to the Mongol army the invention of trebuchet by Mongol engineers One of these four!
The short answer is: infighting and the plague.
Japan
It led to a revolt against the Chinese imperial government,
a period of peace and economic prosperity