Well you might think they must have used a wire saw with a 7″ blade and wide flat steel wedges.

But in the 11th century there was no electricity nor were there wire saws. The approach they used was,

• they established the plane they want to follow by drawing it on the stone,
• proceeded to drill small holes with a primitive chisel and hammer,
• they drilled holes every 6 to 12”,
• inserted half inch wooden wedges into the holes,
• poured some water into these holes,
• left it over night for the wood to absorb water and expand.
• finally, the boulder would split along the established plane.

The wood and water method is till date used in a few places.

Here is a picture from ruins of Hampi where this technique was practiced in the 11th century.