Upper Nile, South Sudan - The reclusive Falata people represent Arab tribes who migrated from western Africa to greater Sudan starting in the 19th century, reportedly settling in the region on their return from a pilgrimage to Mecca.
They are nomadic Muslims who rear vast herds of cattle and move across a wide territory in Chad, southern Sudan and South Sudan's Upper Nile state since Sudan split into two countries in 2011. The total Falata population may number as many as three million.
They claim to have at least 60,000 heads of cattle, but to reveal the exact number would be impolite - akin to asking someone how much money is in their bank account.
Access to these transient, private people is difficult. No organisation - government or NGO - had visited them until recently when Christian aid organisation World Vision arrived to implement its mass livestock vaccination campaign in South Sudan, with the goal of immunising more than 300,000 animals.
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