Ram Shahristan was the ancient capital of Sistan

Sistan

Sīstān is a border region in eastern Iran , southwestern Afghanistan and northern tip of Southwestern Pakistan .-Etymology:...

, in what is now southwestern Afghanistan

Afghanistan

Afghanistan , officially the Islamic Republic of Afghanistan, is a landlocked country located in the centre of Asia, forming South Asia, Central Asia and the Middle East. With a population of about 29 million, it has an area of , making it the 42nd most populous and 41st largest nation in the world...

 and southeastern Iran

Iran

Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...

.

Per Arab geographers, prior to Zaranj

Zaranj

Zaranj or Zarang is a border town in south-western Afghanistan, with a population of approximately 49,851 people as of 2004. It is the capital of Nimruz province and is situated next to Milak, Iran. It is linked by highways with Lashkar Gah to the east, Farah to the north and Zabol in Iran to the...

 the capital of Sistan was Ram Shahristan. Ram Shahristan had been supplied with water by a canal from the Helmand River

Helmand River

The Helmand River is the longest river in Afghanistan and the primarily watershed for the endorheic Sistan Basin....

, but its dam broke, the area was deprived of water, and the populace moved three days' march to found Zaranj.

The ruins of Ram Shahristan were, by the 10th century AD, already swallowed up by the deserts, with only a few remnants of buildings visible.