By definition, you know of them because they survived.
The ones that you know of include the ones that survived.
None of them survived, so you don't know about any of them.
a man works in the office
A fish darts around his bowl.
The main shrine buildings are Kyoto's most extensive.
The people are inside a building.
A female wearing a scarf and sitting on a blue chair.
The children are playing on the playground.