The first campaign world I played in was an amalgam of random setting books owned my my friend Chad's brother.
Will served a bronze dragon that was from Io's Blood Isle, so the Council of Wyrms existed in our wold.
Despite having only part of the boxed set, I remember parts of Kara-Tur were involved in the setting as well. Chad's first character Ramel had businesses in the Isle of Wa and when we played all of our characters crossed over.
The rest of the setting was just random dungeons and cities that we made up on the fly. Those early days were a lot more free. We would just take anything and throw it into the shapeless blob that was our setting. I like the highly detailed settings that I play in today, but there was some freedom of that style that I miss.