Chris Rock: Mystery 7-Year-Old Lived with Family on Pleasure Visa

The 7-year-old South African girl who mysteriously began living with Chris Rock and his now estranged wife for years has been in the U.S. with the help of a visitor visa ... TMZ has learned.

As TMZ reported, a little girl named Ntombi began living with Chris and Malaak in 2008, when she was just 6 months old. There is no evidence the Rock family ever adopted the child, but they treated her like a daughter, making her part of the family and enrolling her in school.

Our sources say Ntombi entered the country on a B2 "visitor for pleasure" visa. The visa allows the visitor to stay in the U.S. for up to 1 year, after which time the visitor must go back to her country and fill out paperwork before coming back.

We're told Ntombi and Malaak went back to South Africa every year and reconnected with the girl's biological family, which included a mom, a dad, a brother and a sister. We're told each time, Ntombi and Malaak returned to the U.S. in short order.