Question: Osiel Cárdenas Guillén was the leader of the syndicate that was part of what country?
Sentence (from "Gulf Cartel"): The Gulf Cartel (Spanish: "Cártel del Golfo" , "Golfos", or "CDG") is a criminal syndicate and drug trafficking organization in Mexico, and perhaps one of the oldest organized crime groups in the country.
Relevant evidence: Yes