Wooden sailing boats anchor at the end of the mangrove-lined tidal channel to Siyu village on Pate Island.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. At one time a petty sultanate under its own ruler, Siyu remained more or less independent and a thorn in the flesh of the Sultan of Zanzibar until troops loyal to the sultan occupied it in 1847 and built an impressive fort there.