go to Rap History Database [4]
(currently containing 1542 records by 1320 artists on 570 labels listed Release Information "only")

Be sure to go to Rap History Mixtapes Database &  Party Series [5]

Discover a huge rap / hiphop / elektro boogie mixtape database with mixes from the Years 1979 - 2007 for each Year these Guy makes a Mix of 4-5 Hours containing only Tracks from that specific Year. So you have like 28 free Mixes for listening and each of them 4-5 hours Playing Time.

Beatschmidtz:
Kay-Zee
Scientist
Soulsonic
CEO Müller