Complex sentence: Negotiations began in January 2003, and agreement was reached with El Salvador, Guatemala, Honduras, and Nicaragua on December 17,2003, and with Costa Rica on January 25,2004; that same month, negotiations began with the Dominican Republic to join CAFTA.
Split into simpler sentences: Negotiations began in January 2003, and agreement was reached with El Salvador, Guatemala, Honduras, and Nicaragua on December 17,2003, and with Costa Rica on January 25,2004. That same month, negotiations began with the Dominican Republic to join CAFTA.