Al-Shabaab has become a top-tier terrorist organization from its extensive revenues. Their wealth is largely based on Islamic taxes that al-Shabaab imposes in accordance with the Koran. It is following the same broad-based sharia revenue model that launched the Taliban from being an obscure students’ movement into an multinational financial hegemon.
http://moneyjihad.wordpress.com/2011/08/16/al-shabaab-economic-powerhouse/
