Do I have to place barbarians on my custom map?

[NULLARC-X]

I'm making a custom map/scenario with civs, city states etc. placed in certain places. Do I need to place barbarians on the map as well in order for them to spawn or will they just spawn automatically?

[Procylon]

From looking at other preset maps like Dales earth maps, barbarians aren't specified on the map, they just spawn randomly.