What was the Original Purpose of Feng Shui?

Feng Shui is the accumulated knowledge of the Chinese civilisation, which started some 4,000 years ago.

They started to live in dwellings on the land, and their main concern was survival. The main considerations were security (from predators and other tribes), safety from nature, how to grow the crops, sources of water and methods to get rid of waste. 

The Chinese documented their observations so that they would not repeat any mistakes and also, find ways to improve the environment for the better well-being of the people.

This wealth of knowledge developed over the centuries. The Chinese Emperors used it to help them rule over the centuries. Feng Shui was used in the design of the infrastructure, which was important for the prosperity of the people. A version of Feng Shui (QiMen DunJia) helped them gain victories in battles.