In the mod when your explorer ships discover a system called "K'lai Klinzhai"
You have stumbled into Klingon space and can expect to see a lot of these.
If you ignore the Neutral Zones and stray into either Romulan or Klingon space you will be attacked.
I originally had the Klingon homeworld in the Qo'noS System however with the proper naming for the systems when I find "K'lai Klinzhai" I am less likely to remember that there are a bunch of deadly Klingons in that system who will not like you venturing into their space.
This is the case with other races where you may not recognise the system until you enter it.