There has been a historical tendency where the genitive adposition oib GEN lost a large part of its place to the relative adposition tan TAN, and at the beginning of the Threehundred Kingdoms period the genitive particle oib GEN was only used to indicate actual possession and the place of origin of common people.

In the North and the East, the genitive particle oib GEN remained in fairly widespread usage, but in the South, around Broi and the Xiy'kahra, the adposition had almost completely vanished during the reign of Emperor Rordal Twuindoal Sedom'Chewir.

.   Séor  oib Tacal verech.zi ga, sero  gedir.ju  doxaz ajun.
    sword GEN Tacal old.AUG   NOM 1sHGH think.CRT 1000  year
    Tacal's sword is very old, I think a thousand years.