When hip-hop started 50 years ago, it was just a curiosity for the record labels. But by the mid-1990's, it was big business.

For artists working outside the major-label system, though, there wasn't much hope of nationwide success.

Then came a group out of Memphis: Three 6 Mafia.

Cultural critic Kiana Fitzgerald has chosen Three 6 Mafia's debut album — Mystic Stylez — as one of hip-hop's game-changing moments.

"This album is in some ways the beginning of the darker side of hip-hop," says Fitzgerald. It's a prime example of the sub-genre they helped to popularize known as 'horrorcore.'

"The members of Three 6 Mafia had an outright obsession with slasher films, like Friday the 13th, The Texas Chainsaw Massacre and Halloween," which Fitzgerald says inspired their chilling, threatening verses — like this one from the song "Live By Yo Rep":

I shall take a thousand razor blades and press them in their flesh/

Take my pitchfork out the fire, soak it in their chest

"It's not for the faint of heart," advises Fitzgerald.

Mystic Stylez also provided a preview to the crunk music that later would dominate hip-hop coming out of the south. Fitzgerald describes their song "Tear Da Club Up" as "one of the most interpolated, reworked, flipped songs in hip-hop history."

"It's something that has really been embraced as a core element of what hip-hop is," says Fitzgerald. "If you hear like a hypnotic, repetitive chant in a hip-hop song today, that comes from Three 6 Mafia."

The group got its start in Memphis, well outside the major-label feeding frenzy happening in New York and Los Angeles at the time. Because they had no label support, the group spent its own money on its debut recording. Founding member DJ Paul once said they invested forty-five hundred dollars into making the first album... and turned it into forty-five million.

That DIY success inspired creators all over the country to try to make it on their own. Kiana Fitzgerald says, "Three 6 Mafia laid the groundwork for the late-2000's to the mid-2010's... And that was one of the more exciting times in contemporary hip-hop. It also inspired the SoundCloud rap movement."

'They did it with what they had in their pocket and in their mind and in their heart. And they were successful because they wanted to create something that really spoke to their region and their lifestyle."