How are hillsides farmed?
The way hillsides are farmed generally depends on the steepness of the hillside. Gentle slopes can be farmed the same way flat land is farmed.

Steeper slops require the hillside to be divided into terraces. The steeper the slope, the narrower the terraces.

Terracing of hillsides in farming reduces erosion because terraces reduce the flow rate of water down the hill. Furrows running down slope can easily transform into erosion gullies.  

Terrace farming has been all over the world and for thousands of years. It is speculated that the Hanging Gardens of Babylon, 


  may have been built on an artificial mountain with stepped terraces, such as those on a ziggurat.


Slopes in the Andes of South America were terrace mining before AD 1000.