Took me a while but I just found the study on the Somali clade expansion times.
Sanchez et al. (2005): "Table 4 presents estimates of ages and expansion times of the Somali E3b1 cluster and the K2 (now known as T) lineages based on Y-STR data using different estimation procedures. By defining the ancestral haplotype as that with the modal allele for each STR system and calculating the average squared distance41 as well as the variance between this haplotype and other variants, we estimated the time back to the most recent common ancestor (TMRCA). In Somalis, the TMRCA was estimated to be 4000–5000 years for the haplogroup E3b1 cluster and 2100–2200 years for the haplogroup K2 (T) assuming a generation time of 25 years. Calculations based on a Bayesian coalescence approach (BATWING expansion time) indicated that the growth of the E3b1 cluster in the Somali population started 1200 years ago (Table 4) with an initial population size of 1037 individuals. A similar analysis of haplogroup K2 (T) resulted in a calculated expansion time of approximately 3300 years in a small male population of 109 individuals."
Like I said, both clades were introduced roughly around the same time. They're far, far older than whatever your particular origin myth says.
