abstract
africa
background
barb
barbed
barbwire
barrier
black
border
boundary
camp
concentration
concept
conflict
crime
danger
dangerous
division
empty
enclosure
fence
forbidden
freedom
guard
hatred
iron
isolated
jail
metal
military
prison
private
protect
protection
racism
razor
safety
security
segregation
sharp
sign
silhouette
sky
space
steel
war
warning
white
wire