You say billions of years in existence?
Thought they originated in Japan?
nah, The Hand worship a demon called The Beast.
The Beast may or may not be one of the fallen angels/watchers.
the folks who started worshiping him predate humanity and were killing stuff cause fukk God.
That's how The Hand started
I only know about the Iron Fist Netflix version. But I thought they originated in Iron Fist's dimension.
Hydra is my pick. The way they ran thru the buildings in Winter Soldier and AoS was .
MCU wise, sure.
comics wise, nah.