Simplify the following text for a Grade 10 native English-speaking person.
Original: The city of Dubai has a free trade in gold and till the 1990s was the center of a `` brisk smuggling trade '' of gold ingots to India , where gold import was restricted ( read the novel Dubai by Robin Moore ) .
Simplified: Dubai has a free trade in gold and , until the 1990s , was the hub of a `` brisk smuggling trade '' of gold ingots to India , where gold import was restricted .