Egypt relied on what to build pyramids?

Answer 1

The ancient Egyptians made use of a plentiful supply of limestone. In the case of the Giza complex supplies of limestone were available from quarries close to the site.

The river Nile was also important supplying a transport link for supplies of other raw materials such as wood for scaffolding and sledges, copper for tools, papyrus reed ropes and food.

The Nile provided mud to make bricks for the ramps and for main structure of later pyramids.

Then there was the matter of labour provided by thousands of peasant farmers who could not work their fields during the annual flood of the Nile.