Iraq consists of 19 governorates, also known as "provinces". Per the Iraqi constitution, governorates can form a federal region. Four governorates, Erbil, Sulaymaniyah, Halabja and Duhok, constitute the semi-autonomous Kurdistan Region. Baghdad and Basra are the oldest governorates. The second most-populous one, Ninawa is in the upland region and has a cooler climate of the north-west.