World activities

As time passes in Dwarf Fortress, certain activities happen outside of the player's influence, without their direct input. This is what is usually referred to as "world activation".

Historical figures can get married have children and do their various jobs, outside your fortress. And all of their children do the same as they are also historical figures.

NPC Sites are built, conquered, destroyed and reclaimed while playing.

Nobles, depending on their specific position will either be inherited by another historical figure or assigned to a new historical figure by the parent civilization when the position is vacated or they have an unfortunate accident.

Armies move around the map while playing, for various reasons, including site invasion (including but not exclusive to the player site), harassment, searching for work, reclamation of sites and more. Due to this, invaders now need a reason to invade the player's site.

This is a common cause, if not the only one, of the DF2014 complaint, "nobody attacks me any more". While the issue has been discussed in great detail on the Bay12 forums, it is generally agreed that being neighbours with invaders will help, as will being in an easily accessible location close to as many of their sites as possible.