I would suggest creating a database link from DB_1 to DB_2. Let's assume the database link is created in DB_1 and connects to DB_2, and is called db2_link. You can insert across the database link with a command similar to the following:
INSERT INTO dest_table@db2_link SELECT * FROM source_table WHERE date_column BETWEEN first_date AND last_date;
The "@db2_link" tells Oracle that the table is in a remote database accessed by the database link you created. The Oracle Administrator's Guide gives complete details on how to set up the database link. Pay particular attention to Part VII, Distributed Database Management. Chapter 29 shows you how to create a database link and use it in your SQL statements.