1)how did muhammad's successors expand the arab empire after his death ?
2. why was there tension over who should rule the empire after the death of muhammad ?

1) Muhammad's successors help expand the Arab empire after his death by suppressing tribal, political and religious uprisings. They united the Muslim world. They defeated and conquered other territories.

2) There was tension over who should rule the empire after the death of Muhammad because he did not have a son and never named a successor.