Sanguis, Sudore et Iubentium
Arena
First all the Zones were painted a Dark Brown to create a Base color and defining lines between each Zone.
I then painted the whole surface with a Yellow Ochre. This is the same color I use for the minis bases. I had it color matched at HomeDepot. For $5 I get a lot of paint exactly the color I need.
Next I dry rubbed a 50/50 of Light Grey and Yellow Ochre to begin highlighting each Zone. I want the Zones to be lighter then the surrounding sand, so I'll let this all dry overnight and asap start dry brushing the sand and then come back to the Zones. 
a great project the Arena and figures look fantastic @henrileite