ShaDynasty
Chaos - The Album
2004/2005
Crunk
Start of snap
TI
Wayne
Jeezy
Gucci
DJ Toomp
Kanye
DJ Drama mixtapes
Houston hits mainstream
Three 6 Mafia hits mainstream
every artist or producer today can draw their roots and inspiration from the intersection of those artists and sub genres/cultures in 04/05
But that's not the same as when the shift happened. That just says artists growing up were influenced by that stuff.
Around 1991/1992 there was a clear shift, Hip Hop production stopped relying on the same old techniques and started experimenting and breaking into new sounds and styles like Dr. Dre's smooth and musical compositions, Jazz rap, the Wu-Tang sound. The difference between the beats on Paid In Full in 1987 and the beats and song compositions on Low End Theory in 1991 is a fukking chasm.
1997 was another clear dividing line for Hip Hop, you had big mainstream rap records from Biggie, Puffy, Will Smith, Wu-Tang, Missy etc. After that it just grew bigger as an expansive cultural force.
Things start to get murky in the last 10-12 years because it has so much to do with the internet and genres crossing over with each other. Kanye might have started the shift with 808s & Heartbreaks, but it took a few years for people to catch on and start taking the next step with that sing/rap style, which also coincided with soundcloud and other music sharing sites blowing up.