Archimedes burnt the ships of many enemies with the help of sunlight and focused through spherical or parabolic mirrors.

In china people many began making mirrors with the use of silver mercury amalgams in 500AD. 

In olden days people used water in a bowl as a mirror

Parabolic mirrors were described by the physicist Ibn Sahl in the 10th century

By the 11th century, clear glass mirrors were being produced in Moorish Spain.