Langeroud or Langerod is situated on the slopes of the mountains, 340 km. from Tehran, enjoying a mild and humid climate. It is irrigated by the Shalman and Langerood Rivers. Langerood was once the bed of the Tetis Sea, and in the reign of Dariush III (Darius), the last of the Achaemenian monarchs, it was amongst the 127 provinces from where the sea had retreated.
The word Langerood was for the first time mentioned in the year 512 AH., coinciding with the reign of "Soltan Mohammad Ben Malek Shah Faramarz Ben Mardan Shah Langeroodi", who escaped from prison, and with the help of Alla'ud Dowleh Mazandarani went to Langerood.
In the Safavid era, specially during the reign of Shah Abbas, Langerood was a city of important historical events. Nader Shah Afshar also paid due attention to this city. He chose Langerood as a headquarter and base for defeating the Tatars of eastern Mazandaran as well as a center for the development of trade, and a shipyard for gaining access to the Caspian Sea.
Today, this city is one of the important cities of Gilan.