Mesopotamian Arabic has two major varieties: Gelet Mesopotamian Arabic and Qeltu Mesopotamian Arabic. Their names derive from the form of the word for "I said" in each variety.^[5] Gelet Arabic is a Bedouin variety spoken by Muslims (both sedentary and non-sedentary) in central and southern Iraq and by nomads in the rest of Iraq. Qeltu Arabic is an urban dialect spoken by Non-Muslims of central and southern Iraq (including Baghdad) and by the sedentary population (both Muslims and Non-Muslims) of the rest of the country.^[6] Non-Muslims include Christians, Yazidis, and Jews, until most Iraqi Jews were exiled from Iraq in the 1940s–1950s.^[7][8] Geographically, the gelet–qeltu classification roughly corresponds to respectively Upper Mesopotamia and Lower Mesopotamia.^[9] The isogloss is between the rivers Tigris and Euphrates, around Fallujah and Samarra.^[9]

During the Siege of Baghdad (1258), the Mongols killed all Muslims.^[10] However, sedentary Christians and Jews were spared and northern Iraq was untouched.^[10] In southern Iraq, sedentary Muslims were gradually replaced by Bedouins from the countryside.^[10] This explains the current dialect distribution: in the south, everyone speaks Bedouin varieties close to Gulf Arabic (continuation of the Bedouin dialects of the Arabian Peninsula),^[10][11] except urban Non-Muslims who continue to speak pre-1258 qeltu dialects while in the north the original qeltu dialect is still spoken by all, Muslims and Non-Muslims alike.^[10]

Gelet dialects include:^[9]