What about nations that have disintegrated due to tribal disagreements? The nation of South Sudan, most recently, was formed when the Southern tribes seceded from the larger Sudan. The nation of Somalia may be
teetering on the brink of failure due to a protracted war, which, although is
globally interpreted as a war between Islamists and the Western-backed Somali government is much a war among Somali clans. What about the Sunnis, Shiites, and Kurds wreaking havoc in the nation-states of Iraq, Iran, Syria, and Afghanistan under the pretext of establishing
a caliphate, while the whole fiasco is, largely, a fight for domination between the warring Arabic tribes? The above examples should suffice.