Samurai &

In the world, there are a lot of fighting arts with throwing weapons.
Throwing a stone, throwing arrow, and Javelin etc.
They exist all over the world.
In Japan they are known as Shuriken-jutsu

There are some common usages of the Samurai sword.
Cutting, and thrusting are a usual usages of the sword.
However, there is a usage of the sword in the emergency.
That is throwing the sword at the enemy.
The enemy in the distance can be attacked by throwing the sword.
Throwing the sword is surprising attack for enemies.

Old Samurai noticed the effectiveness of throwing swords, and devised ae sword to throw, not only in the emergency.
An effective shuriken blade was devised before long.
The techniques of throwing were developed at the same time.

Thus, Shuriken-jutsu was developed.
It was around the end of the Age of Civil Wars.(over 400years ago)