Simplify the following text for a Grade 9 native English-speaking person.
Original: Princess Margaret , Countess of Snowdon ( Margaret Rose ; 21 August 1930 -- 9 February 2002 ) was the younger sister of Elizabeth II and the younger daughter of King George VI and his wife Queen Elizabeth .
Simplified: Princess Margaret , Countess of Snowdon ( born 1930 - died in 2002 ) is the younger sister of Queen Elizabeth II .