Then the peoples around them set out to discourage the people of Judah and make them afraid to go on building. Ezra 4:3

            While the origin of these individuals is not clear, it’s possible they lived in the area and began to see the exiles return.  Fearing their control over the desolate land would be lost by a revitalization of the temple, they probably tried to stop them.  The easiest answer to this question is also their spiritual enemy…Satan.