This as an important topic that needs to be addressed in a serious manner.
I truly mean this when I say this (no trolling), but I do believe with good reason that it is best to stick to marrying within your tribe. The most healthiest marriages I've observed have been between people from the same tribe, and furthermore most were people who were from the same clan within that given tribe. The families are much more accepting of the marriage and want it to work, and consequently they will help smooth any natural conflicts that arise between them. Moreover, your children will share the same tribal heritage and family that you shared if you place any importance on that (as most Somalis do). You won't also have to deal with tribal skirmishes and your children won't have a problem visiting or living in your ancestral homeland. Seeing as the old nation is currently undergoing the process of balkanization, this is a major issue you would at least have to give some serious thought to.
No woman should be having any trouble finding suitable potentials from her own clan let alone tribe, so this is a non-issue in my opinion. Marriage is already hard enough as it is and the divorce rate among Somalis is staggering, so why add even further unnecessary complications that could dissolve your marriage?