Creating a new "Culture"?

I noticed in the vanilla RTW that the Scythian's are a "Barbarian" faction, which is not true their actually a "Nomad" faction like in Bi. But there's no "Nomad" culture in RTW, Only in Bi. Can I add the "Nomad" culture from Bi? All I really really want is to use the "Nomad" character pictures for more realism...

Hope this isn't to confusing!

You'd need to go through the whole adding a new culture method see here
https://forums.totalwar.org/vb/showthread.php?t=55112

Once you've done that you can copy the nomad pictures from BI and use them for your new culture.