Cruciani et al. (2007) suggest that this sub-clade of E-V12 originated in North Africa (around Egypt and Libya), and then subsequently expanded further south into the Horn of Africa, where it is now prevalent. (See Cruciani et al. (2007), Fig. 2/C.)
Before the discovery of V32, Cruciani et al. (2004) referred to the same lineages as the "gamma cluster", which was estimated to have arisen about 8,500 years ago. They stated that "the highest frequencies in the three Cushitic-speaking groups: the Borana from Kenya (71.4%), the Oromo from Ethiopia (32.0%), and the Somali (52.2%). Outside of eastern Africa, it was found only in two subjects from Egypt (3.6%) and in one Arab from Morocco".
Sanchez et al. (2005) found it extremely prominent in Somali men and stated that "the male Somali population is a branch of the East African population – closely related to the Oromos in Ethiopia and North Kenya (Boranas)" and that their gamma cluster lineages "probably were introduced into the Somali population 4000–5000 years ago".
Hassan et al. (2008) in their study observed this to be the most common of the sub-clades of E-M78 found in Sudan, especially among the Beja, Masalit, and Fur. The Beja speak an Afro-Asiatic language which is associated by most linguists with the Cushitic group of languages found in the Horn of Africa, spoken for example by Somalis and Oromo. They also live along the "corridor" from Egypt to the Horn of Africa. On the other hand, the Masalit and Fur live in Darfur and speak a Nilo-Saharan language. The authors observed in their study that "the Masalit possesses by far the highest frequency of the E-M78 and of the E-V32 haplogroup", which they believe suggests "either a recent bottleneck in the population or a proximity to the origin of the haplogroup."
Tillmar et al. (2009) in their study 147 males from Somalia were typed for 12 Y-STR loci, 77% (113/147) had typical E1b1b1a1b haplotypes. This is currently the highest frequency of E1b1b1a1b observed in any single sample population.