Was somewhere over the rainbow part Wizard of Oz play?

No, "Somewhere Over the Rainbow" is not part of the original L. Frank Baum book *The Wonderful Wizard of Oz*. It was written for the 1939 film adaptation, with music by Harold Arlen and lyrics by E.Y. "Yip" Harburg.

The song became iconic and associated with the story, but it wasn't part of the original source material.