Simplify the following text for a Grade 5 native English-speaking person.
Original: Thá há '' 9X ( literally meaning 9X Generation , often referred to simply as 9X ) is a Vietnamese term used to describe people born during the 1990s .
Simplified: Thá há '' 9X ( The 9X Generation ) is the group of people born between the years 1990 and 1999 . This is a Vietnamese term