Probably the oldest and biggest mexican underground hiphop crew, "Obson Most Wanted" is the Obregon Sonora (Ob-Son) City based clique, including groups like:
Yostailingo OMW (the group)
[362 Rappaz]?
[Atake FDD]?
(mc-producer) Drez?
[Obson Clan]?
(mc) [Tavo Ice]?
4DP?
HMO?
[Santos Y La Mata]?
[Skuadron de Atake]?
(mc) Luistyle?