 It has also struggled in this task, for which it is looking back to Libya's first constitution in 1951.Even before the 2011 revolution, former Yemeni president Ali Abdullah Saleh’s regime’s legitimacy relied on a patronage network based on the entrenched Yemeni tribal system, effectively tying Saleh’s political legitimacy to the tribes’ much more established and trusted socio-political legitimacy.Yemen is historically tribal, with tribes being responsible for defense, keeping the peace, protecting and encouraging trade and markets, and either prohibiting or facilitating travel.