Sanchin is the foundational stance of goju ryu. This writer has not come across it in other systems. It is simultaneously strong, and quick to move from.
Sanchin is formed by having the feet shoulders’ distance wide (at the outside of the feet), with one foot forward pointed 45 degrees inward with the edge of its heel in line with the end of the big toe of the other foot.
Movement is smooth. Foot slides lightly across the floor, always touching without weight until it is settled into its new position.
Weight is evenly distributed across both legs, centered just behind the ball of the foot.