Which of these martial arts originated in India in the 400s BC?
Kshatriya was a martial arts developed in the centuries before Christ's birth. Most likely it was developed by a Buddhist monk named Bodhidharma (448-529 AD) who used the exercised for spiritual reasons more than for self-defense.
Kalarippayattu martial arts originated in Kerala in India. This is thought to be the oldest form of martial arts. Other martial arts from India around the 400 BC's is Silambam.
Karate was the martial art that originated in India in the 400s BCE. It is a striking-based martial art. You can learn more about karate at http://www.ask.com/wiki/Karate.