Forlan struggled in Italy last season.
"I played very little at Inter, so I quickly left when I heard of the possibility of moving to Brazil with my family," the 33-year-old told Calcio News.
"I felt it was the right time for a change. I have closed that chapter in my life.
"The Brazilian league is difficult, there are six or seven teams fighting for the top four places. You have to play good football."