Reunification (noun)

1. The act of reuniting or the state of being reunited, especially of a country or group that has been divided.
2. The process of unifying two or more separate entities into a single entity.

Origin:

Late 19th century: from re- 'back' + unification, on the pattern of reunion.

Examples:

1. The reunification of Germany was a major event in modern European history.
2. The reunification of the separated families was an emotional moment.
3. The reunification of the two companies was a successful business move.
4. The reunification of the divided communities was a step towards peace.
5. The reunification of the broken pieces was an important part of the puzzle.