First, the group has attempted to exploit local grievances and leverage established militant networks. In Afghanistan and Pakistan, for example, Islamic State leaders reached out to disaffected Taliban commanders.
Following the death of several Pakistan Taliban leaders, Hafiz Saeed, who is currently the head of Islamic State's South Asia branch, became increasingly disenchanted with the Pakistan Taliban. Saeed had apparently been one of the main contenders for the Pakistan Taliban's top spot, but he was passed over. This discontent provided an opening for Islamic State, which began to woo Saeed and his network. Islamic State used a similar strategy with disaffected Afghan Taliban in Helmand and Farah provinces.
Second, Islamic State has given money to prospective allies. The group has accrued substantial financial resources in Iraq and Syria from smuggling oil, selling stolen goods, kidnapping and extortion, seizing bank accounts and smuggling antiquities. In Nigeria, for example, Islamic State used its booty to aid cash-strapped Boko Haram, which had suffered military setbacks at the hands of the Nigerian and neighboring government forces.
Third, Islamic State's victories in Iraq and Syria, which have been broadcast around the world by an effective social-media strategy, have attracted more sympathizers across the globe. The group has been able to retain--and, in some areas like Ramadi, to expand--control of territory in Syria and Iraq, despite a withering U.S. air assault and Iraqi and Syrian government offensive operations. These successes have attracted a coterie of followers in Africa, other countries in the Middle East, and Asia.