Kenya, Pate Island, Siyu. Siyu Fort. The Sultan of Zanzibar in the middle of the 19th century built this impressive fort at the end of the mangrove-lined tidal channel leading to Siyu village on Pate Island. Troops were garrisoned there to finally bring the troublesome inhabitants of the more or less independent petty sultanate of Siyu firmly under his rule. The fort is now undergoing extensive repairs after years of neglect.Siyu was founded in the 15th century and in its heyday had 30,000 inhabitants; there are now less then 4,000 people living there.