Because the origins of Palestine are Roman designation. Palestine encompassed all of Judea and Samaria including all of Jerusalem , Gaza, Jordon, Lebanon, and a big swath of Syria. At that time the major population were the Hebrew people otherwise known as Jews to you. So until you agree that the Hebrew people were at least also on their ancestral land there is no use talking to you or Abbas.
German authorities accused of playing down refugee shelter sex crime reports (Reuters)
from the article: Palestinians to ask that Obama personally kickstart peace process