No. Ninjas are japanese assassins.
Yes, ninjas came from China.
Ninjitsu (also known as ninpo), the practice of martial art, strategy, and tactics of unconventional warfare and guerrilla warfare comes from Japan and is practiced by the shinobi (outside of Japan they were called Ninja). A female practitioner is called a kunoichi.
They came from japan in the 1700's. The were not as well known as