Boundary
The dirt where you just stand and see is a boundary. You don't want to cross the boundary, you just stand there and see over it. As a general rule, you can stand in the dirt and see beyond boundaries, but you don't usually cross them.
きょう
さかい
None
The boundary you're looking at now is the Kyoto (きょう) boundary. Kyoto is one of the most famous places in Japan, so you can imagine its boundary is really clear and marked by all kinds of boundary signs that say KYOTO.