khussain,

The old datafile has a different creation scn than the datafile from the new tablespace. Since the tablespace was dropped, the database does not know or care about the previous datafile. When you created the new tablespace, that is the new point of reference for the database.

ORA-01203: wrong incarnation of this file - wrong creation SCN is because the database is expecting the creation scn from the newly created tablespace and your datafile contains an older creation scn.