Communicating on mountain sides

What are those symbols on the side of this mountain? How do they get there? Who puts them there? And why?
We took both of these pictures in Ollantaytambo which is part of the Sacred Valley in Peru.

The Inka's designers and architects modified mountains
to pay tribute to their gods. Ollantaytambo is a settlement
of the Inka's elite from the mid 1500s. Find the
 face in the middle left section of this image. Probably
represents an important god. (The dominant feature in
the middle are storehouses for the harvest)

Signage cut into mountains was a
common sight in Peru. This one
we spotted in the Sacred Valley. They
are usually political in nature and may
 promote political ideas.

In Peru we encountered a variety of symbols cut into the mountain sides. These were often visible from miles away and usually served political purposes: they promoted a political party or candidates for mayor or parliament, for instance.

This form of 'communicating' reaches back a long time in Peru. For instance, even though the Inca Empire lacked a written language, it did not lack in scientific and communicative prowess. It designed its Sacred Valley outside of Cuzco, Peru to mirror religious aspects of the Milky Way as they perceived it.