Despite having around 30 sequels to his name, this is the only official sequel to the original 1966 Django. It's also the only sequel where Franco Nero reprises his role.
The two old gunfighters in the beginning say that Butch Cassidy (died 1908) and Wyatt Earp (died 1929) are both dead. So the earliest year that this movie Takes place is 1929 or the 1930s.