A new world began after the Great Flood. All of humanity would spread out from Ararat — after a self imposed bottleneck at Babel — into all the world. The descendants of Shem, though, were somewhat less scattered. The LORD would chose to use this branch of Noah's family to bring the promised "seed of the woman" into the world.[1]
See Israelites for the descendants of Jacob (a.k.a. Israel), Ishmaelites for the descendants of Ishmael, and Edomites for the descendants of Esau (a.k.a. Edom).