To the southeast of Capital city of Tehran, just beyond that city's vast urban sprawl,the ancient city of Ray lies; settling in the Ray began about 6,000 BC and was resided by Aryans about 6,000 years ago.
In the per-Median era, it was called Rhagae and in Classical Roman geography it was called Rhagae.
In the past millenniums, Rey has undergone many ups and downs, floods and earthquakes. The city proudly survived massive and destructive Arab and Mongolian invasions and plundering, which left serious scars.
Archaeological evidence indicates the city was important during the Achaemenian (559-330 BC) and Sassanian (224-637 AD) periods. Ray was the regional capital in the 11th and 12th centuries, before being plundered by rampaging Mongols in the 13th century. 
There is a hill with a spring that its history starts when ancient cavemen stopped living in caves in the region, they settled on the banks of the hill. Also remnants of a split rampart on top of the hill still exist.
During 1933-6 the hill was excavated by archaeologists from the Boston Fine Arts Museum and the University Museum at the University of Pennsylvania headed by Erich Schmidt, which resulted in the discovery of 7,000-year-old artifacts. Some of the discovered objects are displayed at museums in Iran, Chicago, and Philadelphia. Ray today has been absorbed into the Greater Tehran metropolitan area.