In recent decades, Sanaa has grown into a multipolar city, with various districts and suburbs serving as hubs of commercial, industrial, and social activity. Their development has generally been unplanned by central authorities. Many of them were initially set up by new arrivals from rural areas. Increasing land prices and commercial rents in the central city  has also pushed many residents and commercial establishment outwards, towards these new hubs. Souks have been especially important in the development of these areas.