Two sets of Mongols, WTH

I held off my own, barely for a while, against them with my random relocation with England and the Middle East Migration in my current campaign. Well, after defeating the mongols they came back again. I thought when a faction is gone they are gone, now they are back and just attacking me. (Okay I cheated with the Toggle_fov to see, then turned it right off when I am done.)

Another bunch of stacks, and me FORGETTING to build Balista Towers again. Urgggg. At least I have a bunch of troops this time around capable of taking them down.

Got to love the English.

I guess if they get annialated again they will come back a third time. How do I get rid of them for good too?

They come like in total 3 stacks i think...
first is biggest so if you handle it, you handle the others.
Prepare for Timurids and Black death by the way...