Postal codes in Azerbaijan

Postal codes in Azerbaijan consist of four digits. 
The four-digit postcode shows the nationwide format "AZ NNNN". The first two digits show the regions of Azerbaijan in accordance with the modern administrative divisions, including the Nakhchivan Autonomous Republic and occupied Nagorno-Karabakh.
From 1970 until 1991, when Azerbaijan was part of the Soviet Union as the Azerbaijan SSR, the entire territory of the Soviet Union used the six-digit postcode "37NNNN". After gaining independence, Azerbaijan switched to the current four-digit postcode.